Table of Content
A rain jacket is by far the most popular piece of waterproof gear for keeping dry on the trail. Whether you are hiking in the rain, sleet, snow, or navigating an overgrown trail with wet vegetation, a rain jacket will outperform an umbrella or poncho any day of the week in terms of weight, durability, and protection.
A waterproof coat typically is the outermost layer and can be worn alone in the summer or with an insulated jacket as part of a layering system in the fall and winter.
But beware, buying a rain jacket is not as simple as it sounds.
A lot of technology and testing goes into the design of these jackets. When shopping, you'll encounter waterproof ratings, breathability ratings, DWR, and sealed seams.
We explain this jargon and provide insightful tips so you can choose the right rain shell to pack for your next adventure dow below. Let's get started with reviews of the best down jackets available on the market today.
|Outdoor Research Helium II||6.4 oz||$160|
|Montbell Versalite||6.4 oz||$199|
|Enlightened Equipment Visp||4.93 oz||$200|
|ZPacks Vertice||6.2 oz||$260|
|Frogg Toggs Poncho||7.8 oz||$16|
|Skylight Gear||2-5 oz||$140|
|Montbell Rain Trekker||6.9 oz||$169|
|Arc'Teryx Zeta SL||10.9 oz||$300|
|Marmot Precip Eco||10.58 oz||$100|
|Outdoor Research Motive AscentShell||10.9||$199|
|Columbia EvaPOURation Jacket||10.56-12.8 oz||$100|
|Black Diamond Stormline Stretch||11.3 oz||$150|
|REI Co-op Rainier Rain Jacket||13 oz||$90|
|Marmot EVO-dry Eclipse||14.8 oz||$250|
|Patagonia Rainshadow||14 oz||$199|
|Columbia Outdry Reign||12.8-16 oz||$150|
Best Ultralight Rain Jackets
Outdoor Research Helium II
Fabric: 2.5L Pertex Shield+ and 30D ripstop nylon
Weight: 6.4 oz
Why we like it: Top pick for packability
One of the most compact rain jackets on the market, the Helium II stuffs into an interior pocket that doubles as a stuff sack and packs down to the size of a Clif Bar. It is ultralight, making it an ideal rain jacket to throw in your pack as a just-in-case jacket. It is best suited for the occasional rain shower and will not stand up to extended rain or rough terrain. Not as full-featured as some other rain jackets, there are no pit zips for ventilation, no hand pockets and only an elastic at the cuffs.
Fabric: 2-layer Gore Windstopper and 10-denier Ballistic Airlight ripstop nylon
Weight: 6.4 oz
Why we like it: Top pick for cutting weight in your pack without sacrificing features
The Montbell Versalite was designed to be lightweight, waterproof, and breathable. The jacket is cut using Montbell's K-mono cut which uses a single piece of fabric to cut the jacket. As a result, there are fewer seams to leak. Minimizing the seam stitching and sealing also reduces the weight on the jacket. Not only is the Versalite extremely lightweight, but it also is full-featured with generously-sized pit zips that extend down the arm, velcro cuffs, and an adjustable hood.
After being stashed away a few times and under some very heavy rain the jacket did begin to feel wet and damp from the inside, making it not the most durable or protective option in more rugged and harsh conditions.
Enlightened Equipment Visp
Fabric: Waterproof/breathable ePTFE membrane, 7D ripstop nylon, and a soft tricot lining
Weight: 4.93 oz
Why we like it: Top pick for runners and getting active in the outdoors
The Visp rain jacket by Enlightened Equipment is one of the lightest rain jackets on our list. The coat uses an ultralight 7D ripstop nylon with a waterproof and breathable membrane on the inside. Very breathable, the Visp can be used for high-intensity outdoor activities in light rain.
One of our favorite features is the drop tail hem which lengthens the back of the garment so it won't ride up when wearing a backpack. Enlightened Equipment makes most of its gear from its Winona, Minnesota location so you'll get an attention to detail that you can find in the mass-produced coats.
When put to the test, the jacket beaded up water effortlessly for most of its use and we didn't notice any clamy feeling in the jacket after constant rain exposure. The main drawback we noticed with is the lack of breathability and heat retention after warming up.
Fabric: Zpacks custom waterproof breathable fabric, 7D ripstop nylon, and a tricot lining
Weight: 6.2 oz
Why we like it: Top pick for ventilation and breathability
The Vertice is a three-layer rain jacket made from a proprietary waterproof and breathable fabric made specifically for Zpacks. It is amazingly light and breathes better than most competing rain jackets. There also are two pit zips for even more ventilation. It not only breathes, but it also keeps you dry even in heavy rain. The zippers are water-resistant and have a storm flap on the inside, which helps to keep the rain out. Similar to most rain jackets, all the seams are fully taped.
The Vertice is a minimal coat with a single chest pocket that is used for storage and doubles as a stuff sack. It packs up compactly and takes minimal space and weight in your backpack. It has a hood that stores inside the jacket and is large enough for a small helmet when opened.
Frogg Toggs Poncho
Fabric: Breathable and waterproof nonwoven polypropylene
Weight: 7.8 oz
Why we like it: Top pick for tight budgets
The Frogg Toggs poncho is popular among long-distance hikers because it is so lightweight and affordable. The poncho will keep you bone-dry in the rain and is naturally ventilated so you won't get soaked from sweat. It has side snaps so you can open and close it as needed. It has a roomy hood with a drawcord for adjustment.
The biggest detractor to the Frogg Toggs Ultralite 2 Poncho is its durability. The polypropylene fabric may tear if it snags on a branch or scrapes up against a rock. On the upside, it is recyclable so you don't have to throw it away when it reaches the end of its life.Shop Men's Shop Women's
Fabric: Silnylon Jacket
Weight: 2-5 oz
Why we like it: Top pick for ultralight custom-made rain gear
A rain jacket that weighs under 5 oz? You better believe it. Skylight Gear is owned by a guy named Spencer and is a small company you can find over on Instagram. Spencer specializes in making custom jackets based on personalized measurements, and his designs are seriously lightweight without cutting on important features like snap wrist adjustments, an adjustable hood, a waterproof zipper, and pit zips. Besides jackets Spencer is also happy to offer other items like bivy's, backpacks, fanny packs, and more, and plans to keep expanding on other clothing designs. Due to the personalization of the items, expect some wait time, though the products are undoubtedly worth it.Available at Instagram
Montbell Rain Trekker
Fabric: 2-layer GORE-TEX Infinium Windstopper, 20-D ripstop nylon
Weight: 6.9 oz
Why we like it: Top pick for a lightweight 2021 release
The newly updated 2021 version of the Montbell Rain Trekker has cut back on its weight, shed a layer, and seriously upped its breathability and water-resistance game.
It's about 3 oz lighter than the previous version and is now a 2-layer jacket instead of a three. Its water-resistance level is 30,000mm as opposed to the previous 20,000mm and breathability is 43,000K (up from 15,000K!).
Another big change is the material. The Rain Trekker is now made with Gore-Tex Infinium, which is a top-of-the-line fabric for protection against weather while remaining breathable and light. Its pores are 900 times bigger than a water vapor molecule, which increases breathability, wicking power and keeps you from overheating when working up a sweat. It also cut its storm flap across the front zipper for a weight-saving, water-resistant Aqua-Tect Zipper.
The performance of this jacket was by far the most impressive and was a favorite amongst all the models listed here.Shop Men's Shop Women's
Best Lightweight Rain Jackets
Arc’Teryx Zeta SL
Fabric: 2-layer Gore-Tex Paclite Plus and 40D ripstop nylon
Weight: 10.9 oz
Why we like it: Top pick for lightweight, durable protection in extreme conditions
The Zeta SL is part of Arc’Teryx's superlight lineup of outerwear. The 2-layer coat weighs 10.9 ounces which places it right in the middle of most backpacking rain jackets. You get a lot of value for this weight. The Gore-Tex Paclite Plus is outstanding in the rain and will keep you dry even in a torrential downpour. Its equipped with water-resistant zippers and a velcro cuff that'll seal out water. The oversized hood is helmet-compatible and has an adjuster that cinches it down when you don't need that extra room. The brim is even laminated for extra water-resistance. The Zeta SL has a slim but comfortable fit thanks to gusseted underarms and an articulated cut for freedom of movement. A slight drop hem and adjustable hem drawcord ensure a snug fit that won't ride up when you are wearing a backpack.Shop Men's Shop Women's
Marmot Precip Eco
Fabric: Marmot NanoPro waterproof/breathable membrane and 100% Nylon Ripstop 2.4 oz/yd (AM)
Weight: 10.58 oz
Why we like it: Top pick for a tried-and-true, classic first rain jacket
The Precip is the classic rain jacket that everyone buys when they are looking for an affordable, entry-level rain jacket. It's durable enough to withstand minor scrapes and scuffs, yet waterproof enough for hiking in the rain. It has a boxy cut that fits well over layers but isn't oversized. Marmot priced the Precip at the low end, but the company didn't skimp on the extras. The jacket has pit zips for ventilation, velcro cuffs, plenty of pockets and a built-in stuff sack pocket.Shop Men's Shop Women's
Outdoor Research Motive AscentShell
Fabric: AscentShell 3L, 100% Polyester 50D mechanical stretch plain weave with 100% polyester 30D knit backer
Weight: 10.9 oz
Why we like it: Top pick for a 3-layer rain jacket
One of the most price and weight-friendly jackets to come from OR in a while, this 3-layer membrane jacket ticks all the boxes in breathability, waterproofing, flexibility, and durability. Best part? Either that it comes at a 2.5-layer price or that it comes with OR’s special Electrospun membrane construction which provides awesome breathability (especially for a shell). There’s also a built-in stuff sack with a clip to hook to your bag for easy access when weather strikes. But don’t expect many other frills with the Motive AscentShell – to save on weight OR kept the jacket simple, leaving out pit zips, extra pockets, adjustable wrist cuffs, and an adjustable hood.Shop Men's Shop Women's
Columbia EvaPOURation Jacket
Fabric: Omni-Tech Plain Weave 2.5L 100% Nylon
Weight: 10.56-12.8 oz
Why we like it: Top pick for warm climates
A comfy jacket at a fair price, the Columbia EvaPOURation is a good option for moderate hiking through drizzles or to wear while heading out into a misty afternoon around town. It's a thin shell that works well for warmer climates and will keep you comfortable and dry. In cooler conditions, you'd want to add a layer for warmth – good thing the jacket leaves plenty of room for this. The Columbia EvaPouration comes with a Velcro adjustable storm hood with cinch drawstrings, adjustable cuffs, dual hand pockets, and underarm vents.Shop Men's Shop Women's
Black Diamond Stormline Stretch
Fabric: BD.dry™2.5L and 100% Nylon 88% nylon with 12% elastane
Weight: 11.3 oz
Why we like it: Top pick for extra give across the chest and shoulders
The Black Diamond Stormline Stretch is the jacket you want when your outdoor pursuits require mobility and durability in a shell. The stretch is the first thing you notice when you try on the Stormline Stretch. When you move, you can feel the jacket stretch to move along with you. It has a regular fit and feels roomy thanks to underarm gussets that provide a bit more fabric across the shoulders and chest.
Everything about the Stormline Stretch screams quality. The YKK zippers are coated with PU for water resistance. It has pit zips for added ventilation and an adjustable, helmet-compatible hood. Rock climbers will appreciate the pocket stuff sack that has a carabiner clip for convenient storage. You can attach it to your pack and grab it without having to stop.Shop Men's Shop Women's
Best Full Feature Rain Jackets
REI Co-op Rainier Rain Jacket
Fabric: Recycled nylon ripstop (bluesign approved)
Weight: 13 oz
Why we like it: Top pick for casual wear and wind-resistance
Good for cooler climates, the 2.5-layer Co-op Rainier Rain jacket comes from recycled materials covered in a high-quality laminate for strong waterproofing, though, this does cut back on the jacket's overall breathability. Despite decent sized pit-zips, our team of testers found they quickly overheated with minimal exertion. They also found the inside of the jacket clamy after constant rain.
Like the Torrentshell, it is heavier than the other models and isn't quite as packable, but exceptionally durable and waterproof compared to the rest.
The Rainier is a good option for light hiking, casual day-use, or adding overtop layers as a winter shell. Notable features include its ability to withstand winds up to 60mph, and for its price, it comes with some nice bonus features like pit zips, an adjustable hood, and it can pack down into its own pocket. Fit wise expect a roomy jacket.Shop Men's Shop Women's
Marmot EVO-dry Eclipse
Fabric: Marmot MemBrain Eco Waterproof/Breathable Fabric
Weight: 14.8 oz
Why we like it: Top pick for the environmentally conscious
Though steep in price, this 2.5-layer jacket has a lot to offer. It's made from Marmot's Eco-friendly EVO-dry materials that use fewer chemicals and dyes. There’s recycled nylon used in the jacket that’s PFC-free and treated with AquaVent technology, which assists in waterproofness and length of repellency while also reducing staining. The jacket has coated water-resistant protective zippers tucked underneath protective rain flaps, and there are minimal seams for added comfort when carrying a pack (no pesky straps and seam rubbing). Its adjustable hood has a laminated brim that does an excellent job repelling water away from the face. There are also mesh pockets for added ventilation and an adjustable hem, sleeve cuffs, and collar. The jacket’s an athletic fit, though, the “angel-wing movement” allows a good range of motion and keeps the jacket in place when reaching.Shop Men's Shop Women's
Fabric: 3-layer H2No Performance shell: and 12D ripstop nylon
Weight: 14 oz
Why we like it: Top pick for 3-season hiking and everyday use
Patagonia's Rainshadow rain jacket is as stripped down as can be without sacrificing performance. The lightweight coat protects against the weather with DWR, Patagonia's proprietary H2No waterproof membrane and sealed seams. Similar to the Montbell Versalite, the Rainshadow is cut to minimize seams and reduce weight. It also provides extra room in the shoulder and across the back, allowing the jacket to move seamlessly as your hike or climb. It has a streamlined fit that is roomy enough for layers but not so roomy that it feels baggy.
The anorak-style coat has a center zipper that opens half-way down the garment. It provides some ventilation, but not as much as pit zips. Other features include a helmet-compatible and adjustable hood, single drawcord hem and a left chest pocket that doubles as a stuff sack.
A hardier option to the Patagonia Rainshadow is the Patagonia Torrentshell 3L. The Torrentshell is certainly heavier and less packable than the Montbell and Enlightened Equipment jackets. However, its three layer construction feels impressively storm-worthy and ready to take on some harsh four season conditions without completely sacrificing breathability.Shop Women's
Columbia Outdry Reign
Fabric: Shell 100% nylon
Weight: 12.8 oz - 16 oz
Why we like it: Top pick for comfort and wicking capabilities
This flashy, almost futuristic jacket is made from a new fabric from Columbia called OutDry Extreme which is giving Gore-Text a run for its money. The technology beyond the fabric is that it places the waterproof/breathable membrane on the outside of the jacket with a softer wicking material on the inside for added breathability, waterproofness, and comfort. The jacket also features a large hood that allows for plenty of coverage under its adjustable brim, cinch cords at the waist, and pit zips.Shop Men's Shop Women's
Rain Jacket Requirements
Waterproofing: Aim for ratings of 10,000mm and greater.
Rain jackets vary widely in their ability to repel water, which is why there is a market standard that you can use to compare them.
Many manufacturers provide a waterproof rating between 0 mm and 20,000 mm or higher. This number represents the height of water you can add to a 1-inch vertical tube before the material begins leaking.
The higher the number, the more waterproof the fabric. For most outside endeavors, you'll want a rating of at least 10,000mm.
A rating of 10,000 protects you during a light rain, while 20,000 or above is suitable for heavy rain.
Waterproofing is more than just a value. You also should look at:
- The zippers. See if they are waterproof. They will be coated or covered with a layer of fabric to prevent water from seeping through the interlocked teeth.
- Seams. Seams are another weak spot that can leak in heavy rain. They should be sealed to help prevent water from soaking through the stitching.
Breathability: Most jackets are rated between 10K (10,000g) and 20K (20,000g).
Breathability is measured as the number of grams of water vapor that can pass through a square meter of fabric in 24 hours.
Most jackets are rated between 10K (10,000g) and 20K (20,000g). The larger the number, the more breathable the fabric.
You want your jacket to let out sweat that accumulates as you exert yourself while hiking. There is nothing worse than a rain jacket that traps moisture on the inside, leaving you clammy and swimming in sweat.
All breathable jackets face a similar challenge. The pace that the jackets remove water is slower than the rate people sweat. Over time, sweat will start to build up inside the coat no matter what you do.
Pit zips on Patagonia Torrentshell 3L provide some extra additional ventilation
Durability: The higher the denier, the higher the durability.
Denier measures the thickness of the individual threads or filaments used to make the fabric.
- Low (10-20D): Fabrics with a low denier are softer and less durable. Thus, a low denier jacket will be lightweight and easy to pack, but it will tear more easily when you come into contact with branches, thick brush, or jagged rock.
- High (30D+): A higher denier jacket is recommended for winter activities and hiking in thick brush or rocky areas. It'll be heavier to carry and won't pack down compactly, but you'll appreciate its tear-resistance on rough outings.
Sleeve cuffs on Montbell Rain Trekker
Weight: Jackets between 6 and 12 ounces offers a good balance of weight and performance.
There are plenty of lightweight rain jacket options, but most are minimalist jackets made from a lighter weight, less durable material, and little to no extra features like pockets or pit zips.
The sweet spot seems to be 6 to 7 ounces. Anything less than that and you start dipping into the emergency jacket only category which tends to be less durable than an everyday rain jacket.
Adjustable hood on the Montbell Versalite rain jacket
FIT: Plan to wear several layers underneath the jacket
Rain jackets are designed in two basic styles: 1. an athletic fit that is meant to be tight-fitting and 2. a loose, boxy fit for layering.
When purchasing a jacket, you don’t want it too tight in case you want to layer a down jacket or other clothing underneath. As a rule of thumb (although it depends on the brand):
- Athletic cut: go up a size to have that extra room for layers
- Boxy cut: buy true to size as you want to be able to use the adjustments points to secure the openings so rain does not leak inside the coat.
Features: Pockets, Hood, Zippers, and More
Like most backpacking gear, you can choose between minimalist or full-featured jackets.
A minimalist jacket does the job of keeping you dry without all the extras. These minimal jackets ditch the pockets, limit the adjustment options, and remove extra zippers to keep things simple and light. They also tend to be made with lighter material that packs more efficiently in a backpack.
A full-featured coat has everything you need and more. It will include things like:
- Pockets: While daily wear jackets will place their pockets down by the waist, performance jackets place their pockets up higher, allowing you to access the pockets even when you are wearing a climbing harness or a backpack with a hip belt.
- Hood: Some hoods are small and adjust to fit your head snugly, while other hoods are large enough to accommodate a helmet. The bill can be long or short, stiff, or flexible. The best bills are long and have some rigidity, so they hold their shape.
- Ventilation Zips: Pit and side zips are crucial for venting sweat when you start to heat up while exercising. These zippers allow fresh air to flow around your core, cooling you down quickly.
- Drawstrings and Straps: Most high-quality rain jackets will include adjustable waistbands, adjustable hoods, and sleeve cuffs to seal off any openings and create an impenetrable barrier from the rain.
- Built-In Stretch: Stretchable rain jackets tend to be expensive, but they provide undeniable comfortable, especially when hiking, skiing, or climbing. They are also not crinkly like a standard rain jacket.
Chest pocket on the Zpacks Vertice
QUALITY: Look for Defects in the Seams, Zippers, and Inner Layer
Some manufacturers trim costs by minimizing the seam sewing, skipping the seam sealing and choosing low-cost zippers instead of the more expensive and reliable YKK zippers.
Another factor is the waterproofing, especially when buying a used jacket. The waterproof layers inside the jacket may delaminate (separate) with age, and the DWR on the outside may fail, especially if you are rough on your coat.
The DWR treatment can be restored, but the delamination cannot be fixed.
In summary, you should look at the zippers and seams to make sure they will last. If you see a jacket that is flaking or bubbling on the inside, don't expect to stay dry.
Waterproof Explained: Technologies & Layers System
There are three different strategies used by manufacturers to waterproof a coat: laminates, coatings, and DWR.
- Laminate: a waterproof/breathable membrane that is attached to the inside of a jacket's shell material.
- Coatings: also applied to the interior, but this material is spread onto the shell in a thin film. Coatings are less expensive than a laminate layer, but they don't last as long.
- DWR (Durable Water Repellent): applied to the outside of most rain shells. DWR causes water to bead up and roll off a jacket protecting the outer fabric from becoming saturated with water. DWR also can wear off from washing and abrasion, but it can re-applied relatively easily and affordably.
Types of ventilation
- Gore-Tex: the pioneer in waterproof and breathable clothing. It's made of over 9 billion pores per square inch which are 20,000 times smaller than a drop of water and 700 times larger than a water vapor molecule. This precise sizing keeps the rain on the outside and lets your sweat pass through the fabric to the outside.
- eVent: Simiarly to Gore-Tex, it uses a form of Teflon in its waterproof membrane and Pertex Shield.
- FutureLight: Developed by The North Face, it promises to deliver ten times the breathability of Gore-Tex and is lighter in weight than existing waterproof fabrics. It also can be made from recycled materials.
- HydroBot: Made by KJUS, it actively pumps out the moisture using an electroosmotic technology the company developed. The smart fabric is up to 10 times more efficient at removing moisture than existing membranes and can keep up with your sweat rate so you won't get clammy on the inside.
Gore-Tex and its alternatives are not perfect. These pores can only allow so much water vapor to escape. If you are sweating up a storm during a steep ascent, not all of your sweat will be able to escape the pores in the fabric, and you will begin to feel clammy on the inside.
To combat this moisture buildup, you can unzip the pit zips if your jacket has them or undo the front of the coat to let off some steam.
Types of Layers
To protect the delicate waterproofing layers, rain jacket manufacturers often add extra layers to their coats. This is why you will see a jacket designated as a 2-layer, 2.5-layer, or 3-layer jacket.
- 2-layer (entry-level and casual rain jackets): A 2-layer coat attaches a waterproof membrane to the outer fabric and adds a hanging layer, usually mesh, to protect the membrane from wear and tear on the inside.
- 2.5-layer (popular choice for hikers and backpackers): Instead of a mesh hanging layer, the 2.5-layer coat adds a thin protective material on top of the waterproof membrane. These jackets are lighter, more breathable and more packable than their 2-layer counterparts. The inner fabric can feel plasticky for some.
- 3-layer (performance jackets): In this configuration, a waterproof membrane is sandwiched between a rugged outer fabric and an inner protective fabric. These jackets are more substantial and more expensive, but they are also more durable thanks to the extra material.
Softshell vs Hardshell
Rain jackets are often referred to as "shells".
1. Hardshell: Your Typical Rain Jacket
These jackets are ideal for outdoor pursuits where staying dry is critical. They have a rugged out layer designed to ward off rain or handle encounters with branches, rocks and more.
2. Softshells: Stylish, Breathable, but Not 100% Waterproof
These are a completely different type of rain jacket that is more water-resistant than waterproof.
These jackets are made from a soft, stretchable fabric that is treated with a DWR coating on the outside. In a hard shower, the water can't roll off fast enough and will eventually saturate the fabric.
Softshells are more breathable than hard shells and are often worn for intense outdoor activities on a dry day. They tend to be stylish, making them an excellent choice for everyday wear as well.
Some softshells have an inner layer of brushed fleece providing enough warmth that they can be worn as a water-resistant outer layer or an insulating layer underneath a hardshell.
Are 'windproof' jackets a thing?
Most rain jackets are inherently windproof because a coat that prevents rain from penetrating the fabric also prevents wind from entering as well. Some jackets, though, add an extra layer for windproofing but these additions may decrease the breathability.
How to wash a rain jacket?
Wash your rain jacket on a gentle cycle with a small amount of liquid detergent such as Nikwax Tech Wash. Avoid using powder detergents, fabric softeners, conditioners, stain removers, or bleach as they may damage the fabric. We prefer to hang our jackets to dry, but you can toss some jackets in the dryer. Check the instructions to make sure the coat is dryer-safe and to find out what temperature settings to use if it can be dried.
Can I increase my rain jacket's lifespan?
The best way to extend the lifespan of a rain jacket is to keep it clean. Rinse it with water to remove superficial dirt and wash it regularly to remove dirt, grime, and sweat.
How to restore the permeability of a used rain jacket?
After several seasons of usage, a jacket may lose its ability to keep you dry. You can waterproof most jackets as long as the membrane is not damaged. Start with a visual inspection of the jacket looking on the inside to see if the inner layer is separating from the membrane of the jacket. If you notice flaking, bubbling, or partial separation, then the coat is not salvageable and should be thrown away. If the inner layers are intact, you can apply a new layer of DWR to the jacket.
First, wash the jacket and toss it in the dryer as the heat can reactivate DWR. Just be sure the care instructions recommend drying or you can ruin your coat.
There are several ways to waterproof a jacket. You can wash the jacket with a DWR liquid that infuses the fabric with a fresh application of water resistance. There also are spray-on DWR treatments when you want water protection only on the outside. Check out Granger's, Nikwax, McNett or Penguin for a variety of DWR treatment options.