The question of the coldest state in the USA depends entirely on how “coldest” is measured. The designation can refer to the state with the lowest temperature averaged over an entire year (climate) or the location that has recorded the single most extreme temperature event (weather). To determine which state truly holds the title, it is necessary to distinguish between consistent, long-term climate patterns and isolated, record-breaking weather events.
The Coldest State Based on Annual Average Temperatures
The state that experiences the lowest temperatures on a consistent, year-round basis is Alaska, situated far north of the contiguous United States. Its average annual temperature across the entire state is approximately 26.6 degrees Fahrenheit, which is well below freezing for much of the year. This figure is calculated by meteorological bodies like the National Oceanic and Atmospheric Administration (NOAA) using “Climate Normals.”
Climate Normals are 30-year averages of observed weather data, currently using the 1991–2020 period to provide a stable baseline. These averages account for daily high and low temperatures to determine a true measure of the climate. For instance, Fairbanks, in the Interior region, has an annual average temperature around 28 degrees Fahrenheit, with January minimums often dropping to negative eight degrees Fahrenheit.
The consistently cold climate extends into the upper Midwest. North Dakota and Minnesota rank just behind Alaska for the lowest annual average temperatures, with North Dakota recording approximately 40.4 degrees Fahrenheit. These states owe their ranking to exceptionally cold winters, which significantly drag down their annual averages despite having warm summers.
All-Time Record Lows and Extreme Cold Events
While Alaska is the coldest state by average, the metric for all-time record lows focuses on isolated, extreme weather events. The lowest temperature ever officially recorded in the United States occurred at Prospect Creek, Alaska, on January 23, 1971, plummeting to a frigid -80 degrees Fahrenheit. This single measurement represents the most extreme cold ever documented within the country.
The record for the contiguous United States belongs to Montana, demonstrating that extreme cold is not exclusive to the far north. Rogers Pass, a high mountain location, recorded -70 degrees Fahrenheit in January 1954. This record highlights how local geographical features, such as high elevation, combine with large-scale weather systems to produce dramatic drops in temperature.
States like Minnesota, though high on the average cold list, also experience severe, record-breaking events, with its all-time low hitting -60 degrees Fahrenheit. These extreme low temperatures result from specific, powerful intrusions of Arctic air masses. These singular events are important for understanding weather extremes but do not define the state’s typical climate pattern.
Geographical Factors Driving US Cold Climates
The primary factors driving consistently cold climates in the US are high northern latitude, continental effects, and elevation. Alaska’s extreme proximity to the Arctic Circle means it receives less direct solar radiation year-round, which is the foundational cause of its low average temperature. This northern position places it directly in the path of the coldest air masses.
For the contiguous states, the continental climate effect is a major driver of cold. Landmasses heat up and cool down much faster than oceans, so inland regions, like the northern Plains, lack the moderating effect of large bodies of water. This results in significant temperature variation, leading to very cold winters and comparatively hot summers.
The movement of air masses is also critical, specifically the polar jet stream, which separates cold Arctic air from warmer air to the south. When this jet stream weakens, it allows surges of frigid Arctic air, often associated with the polar vortex, to dip far south. Finally, high elevation contributes to cold through adiabatic cooling, where air expands and cools as it rises due to decreasing atmospheric pressure.