Billy is right on the sunny days in Feb. I think some have cabin fever , but some are rutting. Yep, too much time on your hands if you haveseen squirrels having sex. Keep your nuts hidden and your hammer cocked.
I've been a squirrel hunter for nearly forty years. They can be seen most any time of day rain or shine. Consistantly though the best time to see them out in droves is a drizzly rainy damp day. Percentage wise I have limited out more on damp days than any other time. Dusk and dawn on any given day is best.