Montana Weather Summary December 2022
Montana state temps averaged 42 deg below normal on December 22, the greatest below normal day since February 2, 1996, when temps also averaged 42 deg below normal. Some spots were 50°F below normal on the 22nd. The record for the state is 48.5°F below normal on December 24, 1983.
Very cold temps from the 21st through 24th. The first -40°F of the season occurred north of Havre on the 21st. This was 16 days earlier than the average in the years in which this occurs, which is about 95% of the years. Many record low high temps were set. Bozeman had their lowest high temperature of record on the 22nd, reaching only -24°F. Their old coldest high temperature was -22°F on February 2, 1989. Butte had their second lowest high temperature of record, also reaching -24°F. Their coldest is -25°F on January 21, 1962. Elk Park and Newlan Creek both recorded -50°F low temperatures on the 22nd. The last time a temperature of -50°F or colder was reported in Montana in December was in 1998. The last -50°F or colder in the state was February 2019, near Scobey. Very cold wind chill values accompanied the cold. A wind chill of -75.3°F (temperature of -49°F and wind speed of 9 mph) at Elk Park on the morning of the 22nd was likely Montana’s coldest of record. The previous coldest was -69°F at Havre on December 24, 1983. Bozeman reported a coldest wind chill of -67.7°F on the 22nd. This is their second coldest of record. Their coldest of -68.5°F was recorded the morning of December 24, 1983. Dillon reported their coldest of record on the 22nd. A -56.5°F value (temp -36 and wind 5 mph) exceeded their previous coldest of -55.3°F set December 20, 1990.
On the 21st, the temperature dropped 26°F (27F to 1F) in 3-minutes at Dillon. This was their largest of record for a 3-minute period. A 30°F drop (28F to -2F) over one-hour was their largest of record for such period. Their old record was 26°F on December 15, 1979. The Montana records for a 3-minute period and one hours are 32°F at Cut Bank on January 7, 2022 and 50°F at Havre on December 22, 1962, respectively. A sharp cool-down with the passage of this arctic cold front caused the largest daily high temperature change of record at Butte. They went from a high of 30°F on the 21st to a high of -24°F on the 22nd, a change of 54°F. This exceeded their previous record of 53.2°F set from January 31 to February 1, 1989. The warmup that started on December 23rd caused Great Falls to rise from a morning low of -26°F to a late day high of 33°F. This 59°F range was their 15th largest of record and largest since a 61°F rise on December 16, 2000.
The average daily temperature from 21 airport locations across MT was -21.3°F on the 22nd. This was the 19th coldest of record and the coldest day since Dec 21, 1990 (-22.8F). The coldest of record is -28.2F on Dec 24, 1983.
Sustained heavy snowfall over much of the state caused several locations to rank among their top 5 snowiest December’s of record. Havre had their snowiest, Livingston and Plevna their 2nd snowiest, Bozeman MSU their third snowiest, Glasgow, their 4th snowiest and Cut Bank and West Yellowstone their 5th snowiest. For a state average, the month was the 5th snowiest, with the season-to-date the 4th snowiest. This snow also produced the 3rd highest average December snow depth of record.
As a statewide average, this was the snowiest December since 2016 and the snowiest season-to-date since 2010.
This was the highest average December snow depth since 1996.
Sidney and West Yellowstone had their 4th wettest Decembers of record. West Yellowstone’s 5.70-in was their wettest December since 1996. Their calendar year 2022 was their 4th wettest of record.
Bozeman had their third highest December gust of record on the 27th. A line of thunderstorms passing through the area produced gusts to 67 mph at the airport. This was their highest December gust since 71 mph on Dec 10, 1956.
The cold snap in late December produced the highest sea-level pressure value in the state (1057.5 mb near Ulm) since January 2016.
December's sea level pressure range of 73.6 millibars (1057.5 mb near Ulm on the 22nd and 983.9 mb at Cut Bank on the 27th) is the second largest monthly range of record for Montana. December's record was 68 mb in 1955. Largest monthly range is 74.5 mb in January 1962.
The Modified AWSSI (https://mrcc.purdue.edu/research/awssi/indexAwssi.jsp) includes wind, dense fog and freezing rain elements.
State averages are those from 21 airport or nearby locations distributed across Montana.
Great Falls’ average December relative humidity was the highest since 2014.
Locations with most days of warmest or coldest temperature in Montana during the month (2 or more)