As previously stated -

Jan, 1980, -69 degrees F, Fort Greeley, AK. And we trained in it. Of course, daylight was from about 0900 to 1500, more or less. The average temp for the two weeks we spent out in the field was -20 something. We came in, refitted and did a shorter field exercise and it almost broke 0. Coming back to NC was fun, we were in shorts and t-shirts doing PT while the rest of the division was in sweats.