And yet, here we have California (especially LA) with the best cycling weather but barely any safe cycling routes. LA is laughably bad with tons of "bike routes" that are just the rightmost car lane shared with bicycles.
The weather in the Northern Europe really doesn't stop you from being outside any more than the weather elsewhere does (counting forest fires and hurricanes as things that'll keep you indoors).
For ~6 years my wife and I lived in Santa Barbara without owning a car. We'd occasionally rent one to get out of town - there were a couple times I left my bike locked up at the airport for a long weekend.
I used to fantasize about making a documentary called "the disappearing bike" where you would video somebody cycling around town but every time the bike lane disappeared and then reappeared a quarter mile later, you'd show them just gliding across the street without their bicycle.
Even in SB, which has a much more chill attitude on the roads than anything south of Thousand Oaks (as you head into the LA metro area), some drivers would be bizarrely unsympathetic to the fact that you were traversing a short strip with no bike line in order to connect two bike lanes, with reactions ranging from honking, yelling, revving the engine to loudly pass, "buzzing" you by passing much too close, ... but I think it generally follows that rule that most of us are kind and some small constant percentage (5? 10%?) of the world is jerks.