New Mexico here:
my Preference is to hike the mountains between say noon and 3:00 coz the temps are up in the upper 90s - 100s and there aren't as many people around. I did all my centuries in the summer coz - like Kaybee - when the temps drop below 60 I'm cold. I'll take the heat ANY day over cold....course it's a "dry" heat!!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"