Bicycles are the most common form of transport where I live in Umeå, and in the two nearest cities, Oulu and Vaasa. I’ll let you check what the weather is like today.
I’m not advocating bicycles to transport wood (the most common industry here) to the train.
Heat and rain are bigger barriers to bicycles than cold. You could make a case for ice, but you can address that at the infrastructure level. You can make a case for hills, but again, infrastructure (namely, minimizing grade and going around whenever possible). It's a lot easier to wear a coat than it is to wear an air conditioner; if Tw > 30, you are risking heat stroke by pedaling. California, except the far southeast, has generally cooler and much drier summers than most of the United States.
Also, it's +2 in Umeå right now, which is warmer than I thought.
Hah! I've been to Oulu. These people are hardy. Riding bikes in winter near the Arctic Circle is tough work. Yet the bike racks were full in January when I visited a few years ago.
I’m not advocating bicycles to transport wood (the most common industry here) to the train.