There are very few highly populated places where climate would reduce your ability to cycle most days of the year. I'm from Whistler, Canada, I spent a few winters commuting by bike every day, and it's in the Coastal Rainforest, so lots of rain too.

Sure, if you live in Moscow/Anchorage/Montreal/Stockholm/etc, it's miserable for a few months, but the rest of the time, you can cycle.

Plus, cycling in the cold wakes you up even faster than cycling in the heat.