Some days I wear merino wool long johns. Only when it's really cold, though. I've worn them on days I don't need them, and I always overheat. Too much warmth on my chest and I'll sweat a little, too much on my legs and I'll drown in it. Maybe it's just me?
Originally Posted by
TimothyH
What was the weather like during the night?
Sometimes cold air settles into small depressions or low spots when the winds are calm, especially with clear skies. I ride a bit at night here in Georgia and the cold air often settles into the valley's cut by all the creeks around here. It doesn't even have to be valley but even just a slightly low spot relative to the surrounding area. The temperature difference can be profound.
-Tim-
Hot air rises, cold air settles. I've noticed the same thing many times hiking and backpacking in the mountains.