Revisiting the Coldest Temperatures Ever Recorded in the Continental U. S. (credit: Weather Underground)
DISCUSSION: Late January and early February of this year brought an outbreak of frigid arctic air to a large portion of the U.S. with temperatures in the north-central portion of the U.S. the coldest that they have been in over 20 years. Specifically, the coldest temperature measured this year occurred at Cotton, Minnesota of -56F on 27 and again on the 31 January. Including these temperatures this year, temperatures between -55 and -59F have been officially recorded 34 times in our ~150-year observation record over the continental U. S. (there are additional unofficial and/or unverified temperatures that have been measured below -55F). Given that we are past the climatologically coldest part of the year, this current outbreak of unseasonably cold air across the U. S. probably won't set any new record cold temperatures for the year.
For someone who lives in Louisiana, -56F is unimaginably cold. But, even colder temperatures have been recorded in the lower 48 states of the U. S. The map above shows the locations of the 15 official temperatures that have been measured at or below -60F. For the dates when these all occurred, please click here.
Of particular note is the coldest temperature ever recorded in the continental U. S. of -69.7F on 20 January 1954 at Rogers Pass, Montana. This was so cold that the indicator of minimum temperature along with the fluid in the thermometer actually retreated into the bulb of the thermometer. The station that recorded this value existed in that location for only a short time from 1 May 1953 to 28 June 1956. It was installed next to a new mine which turned out to not be very productive. So, the mine and observation station were shuttered after only a short time. In order to achieve such an extreme temperature, conditions have to be just right. Otherwise, such a temperature would occur more often. Indeed, the weather conditions at Rogers Pass the night/morning of 20 January 1954 were ideal for generating extreme cold. In particular, there was fresh snow on the ground, a dry, cold air mass in place, no clouds, and no wind, all conditions very conducive to radiational cooling. In addition, the station was located in a depression allowing the coldest air to sink toward the station. Despite these conditions, and as is typically the case for record observations, this particular observation underwent a robust verification process by the Weather Bureau (precursor to today's National Weather Service). For example, the instrument was tested to make sure it was working correctly and the measurement was checked for consistency with other nearby stations.
The above is a small glimpse into the coldest temperatures recorded in the continental U. S. and a little bit of the story surrounding the record coldest temperature. I suppose one take away from this is that no matter how cold it gets wherever you are in the lower 48 states of the U. S., it could always be worse (i.e., colder).
To learn more about other past historic weather and science events from around the world, be sure to click here!
©2019 Meteorologist Dr. Ken Leppert II