I always thought the hot to cold = getting sick was a myth. We workout inside and go into the freezing cold a bunch (granted for short durations). We workup a nice sweat when digging out snow machine and then cool way off.

I'm also more comfortable with cooler climate but if my math is right 18c = 64 F? I'm not sure what to tell you if 64 is too warm......that seems a bit extreme.

How is your fitness level? Weight? I know a few heavier folks who would always get hot (one lost a bunch of weight and is now always cold!)