We all know that the temperature at the top of a mountain is colder than at the base (usually this is the case… there are, of course, exceptions). But many ski areas don’t have weather stations at both the base and the summit, so it’s hard to know what to expect up top when you’re at the bottom about ready to start your day. Thankfully there is a shortcut
This shortcut is called the Lapse Rate and it describes how the temperature changes with altitude. While the lapse rate is a constant, in the real world the actual temperature can change based on aspects beyond just the physics of the atmosphere, such as the direction the slope is facing, the make-up of the slope (rocks, snow, a lodge) and other factors.
Still, here’s the way to approximate the temperature at different elevations. When the air is dry, the temperature decreases about 5.5 Degrees Fahrenheit for every 1,000 feet gained in elevation. For example, if the base of the mountain is about 3,000 feet lower than the summit and the temperature at the base is 20 Degrees, you could estimate the summit temperature at about 5 Degrees. In practice, the summit temperature can be a bit warmer than this approximation because the ground can stay a bit warmer than freely-moving air just above and around the summit.
When the air is moist, the temperature decreases about 3.3 Degrees Fahrenheit for every 1,000 feet gained in elevation. This includes times that it is snowing or raining, or times that you’re skiing in the fog or in the clouds. For example, if the base of the mountain is about 3,000 feet lower than the summit and the temperature at the base is 20 Degrees, you could estimate the summit temperature at about 10 Degrees. Again, just like with the dry atmosphere example above, I would add a degree or two onto this estimate as areas near the ground can retain just a bit more heat than the atmosphere above and around the mountain.
Air decreases in temperature with increasing altitude because air at higher elevations is at a lower pressure since there is less air above it pressing down. When air is at lower pressure, it expands and cools.
While these calculations are no substitute for finding readings from weather stations, they can help when the nearest official temperature measurement is many mountains away.
Meteorologist Joel Gratz is the creator of opensnow.com and is based in Boulder, Colo.