Minnesota is known for its dramatic seasonal changes, and the arrival of the first snowfall is a major event. The exact timing of the first flakes is highly variable, influenced by atmospheric patterns that shift the onset of cold air. When discussing snowfall, it is helpful to distinguish between a trace amount (flurries that do not accumulate) and measurable snow, defined as a tenth of an inch (0.1 inches) or more. The transition from autumn to winter generally spans from mid-October through mid-November, when the first snowfall is possible.
Statewide Average Timing
The climatological average for the first measurable snowfall across Minnesota falls between late October and early November. The very first appearance of snow, often just flurries or a trace amount, typically occurs earlier, usually during the middle two weeks of October. These early events tend to be transient, often melting quickly upon contact with the still-warm ground. For most of the central and southern parts of the state, the first measurable snowfall is more likely to arrive in the first week of November, reflecting a clear seasonal progression from north to south.
Regional Differences in First Snow
The state’s significant latitudinal spread creates notable differences in when the first snow arrives. Northern Minnesota, including areas like International Falls and Duluth, experiences the earliest onset of winter conditions. The average date for the first measurable snowfall in International Falls is around October 18, reflecting its position as the northernmost major weather station. Along the shores of Lake Superior, Duluth typically records its first measurable snow shortly after, around October 24.
Central Minnesota, encompassing the Twin Cities and St. Cloud, sees its first measurable accumulation approximately two weeks later. The average first date for the Minneapolis-St. Paul metro area is November 4, while St. Cloud averages November 2. Southern Minnesota locations, such as Rochester and Marshall, are generally the last to see measurable snow, with averages falling closer to November 5 to November 12. This north-to-south gradient is a direct result of the continental climate, where the northern tier is more frequently exposed to cold air masses descending from Canada.
Historical Extremes and Influencing Factors
While averages provide a predictable window, Minnesota weather history includes significant anomalies that shift the timing of the first snowfall. The earliest documented trace of snow statewide occurred on August 31, 1949, at the Duluth Airport. The state record for the earliest measurable snowfall was set on September 14, 1964, when International Falls recorded 0.3 inches. These early events are caused by intense, early-season atmospheric disturbances, often involving a strong trough of low pressure pulling cold, Arctic air southward from central Canada.
Early snows can be amplified when an unusually warm and moist air mass, often from the Gulf of Mexico, is drawn into the system’s colder side, increasing available moisture. Broad climate patterns, such as La Niña, sometimes favor a colder and snowier winter season for the Upper Midwest. However, the exact timing of the first significant snowfall remains highly variable and dependent on the path of individual storm systems, as demonstrated by the major Halloween Blizzard of 1991.
Transition from First Flake to Sustained Cover
The first measurable snowfall is distinct from the start of the permanent winter season, as early snowfalls in October and November are frequently followed by a thaw. This occurs because ground temperatures are still relatively warm, making the first accumulation temporary. A more meaningful milestone is the arrival of sustained snow cover, defined as having at least one inch of snow depth continuously on the ground. For the Twin Cities, the average date for the first one-inch snow depth is November 21, while further north, St. Cloud sees this milestone closer to November 15.