Heat buildup (and sweating, hot flashes, etc) are also a byproduct of yoga practice. They call it the "yogic fire".
in your contemplation (not your meditation, your contemplation), the classic strategy is to cast into this fire your attachments, yearnings, aversions, and other worldly hooks.
Finally, this is a good thing. Cold is the opposite of life. More heat is more life force (i.e. strength and vitality). Just dress lighter. I rarely wear jackets in cold weather anymore. It dovetails nicely with my increasing nonchalance to external factors. It's hot, it's cold, it's raining, it's whatever....it just is what it is, and I feel no compulsion to imagine I need to "fix" it.
