I've found I have 2 heat points. After the first 5-10 minutes I feel warm if I start out cold. After 30-40 minutes I need a lot less clothing.

Depending on wind, I'll wear long sleeves and light gloves (cold hands) between 45-50. Above 50 and I shed the gloves. Above 55 is back to short sleeves. Pants don't come out until it's below 40. After that it's expirmentation for me. Depending on the time of the year I'm better acclimated to the cold. I also learned to take wind into account. I have to cover better when it's 0°F with 20 MPH headwinds.

Although anything above 40 I can wear shorts and a t-shirt and just be uncomfortable.