Aren't there normal variations in temperature? Why think it was anything other than that? What's the noteworthy part?
The fact that it was the same spot each night could be explained by the spot being slightly lower than the surroundings and collecting cooler, heavier
air. It could be explained by any number of things, for that matter. A consistantly cool place is not a sign of anything paranormal.
I'm not trying to be dismissive in a discourteous way. Perhaps you're leaving out something important? It can't just be a cold patch of air that
is still bothering you 37 years later, can it?

