For twenty years, I lived six miles or so northeast of Fairbanks, overlooking the Tanana Valley. I worked in town, and when it was really cold in Fairbanks, as in colder than -40, it would be around -20 at our home, which was maybe a couple hundred feet higher than the city.
The weirdest weather phenomena I think I ever ran into involved a hard inversion. I flew a Cessna 185 on skis north from Fairbanks to the Yukon Flats, about 100 miles north. At the time, the only reporting point on the Flats was Fort Yukon, and on this particular day, FYU was reporting -19 F and a light breeze. FYU is just over 400 msl, FAI is 434 msl, and the White Mountains lie between.
I had been trying to get to a site southwest of FYU for several days, but it had been really cold. So, the relatively warm temp of FYU this day was encouraging. Fairbanks, however, was a solid -30 F. That seemed weird to me, since the Fort is generally colder than FAI in winter and hotter in summer. But, anyway....
So, cleared the White Mountains, and descended toward the lake I was headed for. FYU AWOS was still reporting -19 F. My OAT instrument verified about -20 F.
I swung around to land on the lake, which sat in a bit of a depression, and was surrounded by trees. As I descended below the trees, it felt like I was diving into water, and it was astounding how quickly the cockpit cooled off.
I landed, taxied back to the shore, and when I got out of the plane, it was obviously REALLY cold. There was an "official" weather station there, and the thermometer on it read -58 F.
I quickly jumped back in the plane, and departed, using limited throttle. As I came up out of the lake, to about 100 feet agl, the temperature was again about -20.
I never saw such a hard, shallow inversion before or since. The key was that there was a gentle breeze of ~ 6 knots or so, which was mixing the atmosphere above the trees, but that sump and the trees surrounding it were protected.
When I first moved to FAI, I picked up a brand new Cessna 185. That airplane came with the official Cessna "Cold Weather Kit", consisting of two plates with small, rectangular inlets that blocked off the cowling air inlets, and an induction intake plate with a ~ two inch diameter hole in it.
So, first winter, when it got cold, as in -20 or so, I dutifully installed that kit, and off I went. Problem was, if I climbed above 500 or 1000 feet, the engine would start to overheat, because the air at those heights was warmer. But, of course, where I was going was north and colder. The conundrum was to leave the plates in place and stay way low, down in the very cold air (dumb idea) or remove the kit.
I removed the plates on the main air inlets and put some duct tape over the oil cooler, left the induction plate in place and flew that plane for a number of years in very cold temperatures.
MTV