I live in the south (US) and I have yet to see a day during the summer that has been too hot or too humid for me to ride. However, I've seen plenty of days in our "winter" months that I just will not ride. I have ridden in the low 30s with 15-20 mph winds, but I didn't like it at all. At 58, I now will not ride in temps less than 50 F. There are far too many nice days here for me to have to ride when I really don't want to.