There is a good chance that right now, it is raining here in Seattle. It rains more here than it doesn't and we have names for all our different types of rain. Drizzle, misty, dewy, hazy, sprinkle, pouring, dumping, storming and even sideways rain can occur within the span of one day. A fun way to single out the locals from the tourists is simply look for the umbrellas. Seattleites tend to shun the waterproof dome for the more practical jacket, especially the commute-y ones. Cycling with an umbrella, while a visually humorous spectacle, is almost impossible so a good jacket is essential if you plan to bike anywhere.
All waterproof fabrics (for clothing) are basically synthetic sheets with holes tiny enough for water vapor to get through but not full on water drops. To be advertised as waterproof, a jacket has to withstand a level of pressurized water before letting moisture through which is measured in either psi or mm/24hr. Waterproofness at a single moment in time or either over a 24hr period.
A generic light polyester rain/wind coat you might find at Target comes in at about 3 to 5 psi and doesn't even get a waterproof rating. A Gore-Tex or similar style membrane can be rated up to 40 psi and 30,000mm/24hr. Those are the realistic two ends of the spectrum in terms of consumer waterproof fabrics but new technologies are being developed all the time and I'm sure in the not so distant future, we will have paper thin jackets that have adjustable breathability/waterproofness that can charge your phone, heat itself and shoot a bunch of "high-visibility" colored lasers everywhere.
In all honesty, unless you are getting paid to be on your bike, you probably won’t be outside long enough to need anything rated more than 10,000mm/24hr. Biking is also technically exercise (really fun exercise!) so breathability is more of a relevant factor in bike commuting, especially when you spend 10 minutes getting all bundled up in preparation of the big hill you go down first thing in your morning commute where wind chill makes it feel like -30F, only to start sweating as soon the clouds break and you start pedaling.
Wearing a very low breathability jacket while exerting yourself can make for a very clammy and slimy ride. Personally, a thin wool base layer is essential for any water showered biking excursion. Its moisture wicking and heat retaining properties can make even the most plastic bag of jackets feel much better by keeping your salty sweat off you.
If you come check out our clothing some time, you'll notice that a lot of bike clothing manufacturers will add underarm zippers that can open and greatly increase the general breathability of the jacket and bring the total number of zipper pulls on your person to 25 (hey, they are awfully convenient). Waterproof performance clothing doesn't tend to be very stylish but more and more companies are finding that people actually care about how they look and are expanding their lines to accommodate this emerging market. Although, high price tends to keep this out of reach for most people who don't work at Amazon or Tableau.
As for what we stock, Showers Pass is one of the best companies to make waterproof rain gear and their Refuge Jacket is one of our favorites. At just shy of $300, it isn't a cheap piece of clothing but with a 25,000ish mm/hr waterproof rating and huge forward facing underarm vents that scoop air very efficiently, it makes it our best jacket for the upcoming 9 months of falling sky water. Not to mention they are out of Portland (local-ish!) and have an amazing lifetime warranty.
Endura is another great bike-tech clothing company which makes the Lumilite II jacket. At just over $150, it's one of the more affordable of our offerings. I've also probably seen more cyclists wear this water shield than any other. Which may be due to the fact that it is undoubtedly the loudest jacket I have ever seen. With an eye-taxing Hi-vis yellow AND green offerings, a wide array of highly reflective chevrons and an integrated tail light, this is the best jacket for the rider who wants to "take the lane" and let cars know that he has every right to the lane. Pairs well with a handlebar light and head lamp. Rated 10,000mm/24hr with plenty of underarm venting, you'll stay dry, comfortable and VERY VISIBLE.
We also carry a few other brands like Pearl Izumi and Bellwether. These companies have cheaper, not technically waterproof offerings, which lend themselves to more wind resistance. Those two jackets just happen to be ones that we really like and have carried for a long time. We also get new stuff all the time and love to hear what you personally like. For example, at the time of writing this, we just received some of Showers Pass new Crosspoint waterproof gloves which have been very popular out of the gate.
If you haven’t bought one already (you’re streets behind!), a reliable and comfortable jacket is one of the few pieces of clothing that is worth investing in. With all the spray, mist, sprinkles, thunder showers and drops falling from the sky in the next few months, you'll probably be wearing it most of the time.