I live in Portland, OR. October through May, rain is life. Fenders are always installed, rain gear is always in a bag, generator lights are always on, and wool is my friend. Honestly, riding in a light mist or drizzle can be quite nice. Much of the rain here falls into that category.
Commuting and randonneuring happen regardless. For sport/recreational riding, if a ride's planned you pretty much go unless it's super heavy rain - otherwise guys are going to harass you. No doubt there are fair weather cyclists here, but more likely people are into cross, bikepacking, and transportation cycling.
Before moving here, I lived in west Texas for a while. 115F and a sun that's trying to kill you? Screw that, I'll take 45 and rain.