Montana Annual Temperatures and Records

Montana's Temperature Records

Hottest temperature ever recorded: 117 F, Medicine Lake, northeast Montana, 1/14/1954 Coldest temperature ever recorded: -70 F, Rogers Pass, west-central Montana, 1/20/1954 Hottest location ranked by highest average annual temperature: Yellowtail Dam, southern Montana, 50.4 F Coldest location ranked by lowest average annual temperature: Lakeview, southwest Montana, 35.0 F Browning, MT holds the United States record for a 24-hour temperature drop. On Jan. 23, 1916, it went from 44 to -56 within a day - a 100 degree drop. On January 11, 1980, the temperature at the Great Falls Airport rose from –32F to 17F in just seven minutes as a Chinook wind warmed the arctic air. This temperature rise stands as the most rapid temperature change ever registered in the United States. Montana's record for most consecutive days with the high temperature equal to or exceeding 90 degrees was set in July - September 1922 with 38 at Crow Agency, Montana. The record for most consecutive days with the low temperature equal to or below 32 degrees was set in September 1970 - May 1971 at West Yellowstone, Montana with 251 days.

Cold waves, which cover parts of Montana on the average of six to 12 times a winter, are usually confined to the sections northeast of Glacier Park- Miles City line. A few of these cold waves cover the entire area east of the Divide or even the whole State. These cold waves do not now hold the dangers they did years ago before modern transportation, roads, communications, and even heating plants developed to their present levels. However, with temperatures well below 0 degrees Fahrenheit (° F) accompanied by strong winds with blowing snow, these cold waves can be very inconvenient and even dangerous to the careless or inexperienced. In small areas ideally situated for radiational cooling, temperatures can reach lower than -50° F. The coldest ever observed was -70° F at Rogers Pass, 40 miles northwest of Helena, on January 20, 1954. This is the coldest of record for the contiguous U.S. In contrast, the low at Helena that morning was -36° F.

During the summer months hot weather occurs fairly often in the eastern parts of Montana. The highest ever observed was 117° F at Glendive on July 20, 1893, and Medicine Lake on July 5, 1937. Temperatures of over 100° F sometimes occur in the lower elevation areas west of the Divide during the summer, but hot spells are less frequent and of shorter duration than in the plains sections. Hot spells nowhere become oppressive, however, because summer nights almost invariably are cool and pleasant.

Winters, while usually cold, have few extended cold spells. Between cold waves there are periods, sometimes longer than 10 days, of mild but often windy weather. These warm, windy winter periods occur almost entirely along the eastern slopes of the Divide and are popularly known as "Chinook" weather. The so-called "Chinook" belt extends from the Browning-Shelby area southeastward to the Yellowstone Valley north of Billings. Through this belt, "Chinook" winds frequently reach speeds of 25 to 50 mph or more and can persist, with little interruptions, for several days. In January, the coldest month, temperature averages range from 11 for the Northeastern Division to 22° F for the South Central Division. In some areas east of the Divide, January and February can average 0° F or lower, but such occurrences range from infrequent to about once in 10 to 15 years in the coldest spots. Most Montana lakes freeze over every winter, but Flathead Lake, between Polson and Kalispell, freezes over completely only during the coldest winters, about one year in 10. All rivers carry floating ice during the late winter or early spring. Few streams freeze solid: water generally continues to flow beneath the ice. During coldest winters "anchor" ice, which builds from the bottom of shallow streams, on rare occasions causes some flooding.

In July, the warmest month, temperature averages range from 74 for the Southeastern Division to 64° F for the Southwestern Division. This summer warmth is fairly steady, very seldom severe, and is tempered by normal nighttime minima in the 50s and 60s. Miles City, one of the State’s warmest places in July, has a July average minimum temperature of 60 and an average maximum of 90° F. 

 

Montana precipitation averages and extremes, precipitation and temperature data for all U.S. states and Top 10 U.S. climate extremes
Data source: National Climatic Data Center