Staying Warm as a pitcher

It is really hard for me to stay warm when im pitching, I live in Minnesota and we are playing in 50-95+ degree weather. I have tried to stay moving in between innings, wearing a winter jacket. What else could I try?? I stay warm for about 2-3 innings depending on the temp outside. When it is really humid and above 75 or so it really isnt a problem.

Jumping jacks are the quickest, least-demanding way to build and keep a sweat going.

do you wear thermal underwear ?

try a heating pad? In addition to electric, there are devices now that you warm up in a microwave and they stay warm for up to eight hours.