The coldest temperature ever recorded in Montana was -70 degrees below zero at Rogers Pass north of Helena, on January 20, 1954. This is also a national record for the lower 48 states. The warmest temperature ever recorded in Montana was 117 degrees at Glendive, July 20, 1893, and at Medicine Lake, on July 5, 1937.
The temperature at Medicine Lake in northeastern Montana reached 117 degrees on July 5, 1937. This tied the all-time temperature for Montana previously established at Glendive on July 20, 1893. Combined with the -70 degrees Fahrenheit at Roger's Pass in 1954, this makes the all-time temperature range recorded in Montana 187 degrees. This is the most extreme temperature range experienced in any of the 50 states.
The greatest temperature change in 24 hours occurred in Loma on January 15, 1972. The temperature rose exactly 103 degrees, from -54 degrees Fahrenheit to 49 degrees. This is the world record for a 24—hour temperature change.
The greatest temperature change in 12 hours happened on December 14, 1924. The temperature at Fairfield, Montana, dropped from 63 degrees Fahrenheit to -21 degrees at midnight. This 84-degree change in 12 hours stands as the greatest 12-hour temperature change recorded in the United States.
The temperature at the Great Falls International Airport on January 11, 1980, rose from -32 degrees Fahrenheit to 15 degrees in seven minutes when Chinook winds eroded an Arctic airmass. The temperature rose from 47 degrees in just seven minutes, making it the record for the most rapid temperature change registered in the United States.