Labor Day is a federal US holiday, intended to recognize the the efforts, contributions, and achievements of American workers. With roots in the labor-rights movement dating back to the 1800s, it has been celebrated on the first Monday of September since the 1880s, and officially since 1894. Labor Day is always between September 1 and September 7. Most schools also return to session either just prior to or immediately following Labor Day, and as a result, the holiday is often regarded as the unofficial end of summer.
The end-of-summer designation makes sense too. During the first week of September, an average location in Minnesota receives just over 13 hours of daylight (between sunrise and sunset), with day length shortening by about three minutes per day during this time. The longest days, around the summer solstice, average nearly 16 hours between sunrise and sunset, so by Labor Day, Minnesota communities have lost over 2.5 hours of total daylight. Moreover, the sun appears at a much lower position in the sky during early September than in middle-late June, making its light less direct. Shorter days with weaker sunlight ultimately usher in the fall transition season.
The climatology of Labor Day reflects its position on the calendar, with many signs of both summer and fall mixed into historical weather records. Temperatures in the 90s F occur with some regularity; temperatures exceeding 100 F are not nearly as common but have occurred at times in the more heat-prone regions of southern and western Minnesota.
One of the hottest Labor Days on record occurred September 4, 2023, with high temperatures around 102 F reported at Marshall, Theilman, and Brainerd; 101 F at Canby and Gull Lake Dam; and 100 F recorded at Milan, Artichoke Lake, and Long Prairie. It was the hottest Labor Day on Record in the Twin Cities, with a high of 98 F, and a record-warm low of 74 F.
Labor Days of 1913, 1922, 1929, and 1931 also had widespread heat across western or southern Minnesota. On the flip-side, some cooler years have led to frost or even hard freezes in portions of far northern Minnesota, with the 1935 and 1974 Labor Days standing out as unusually cold.
Showers, thunderstorms, severe weather, and heavy rains have also struck Minnesota routinely during past Labor Days. Early September can be quite "active" for severe weather, but few major tornado or damaging thunderstorm events have occurred on Labor Day itself. In 2005, intense thunderstorms in western and northwestern Minnesota produced hail and scattered wind damage. Heavy rains struck much of Minnesota on Labor Day of 1964, with a record 2.16 inches falling in the Twin Cities and 3-4 inches falling from Worthington to Mankato and Wabasha, and throughout the Arrowhead region of northeastern Minnesota.
In the Twin Cities, the average Labor Day high temperature, based on the 1991-2020 climate normal period, is 78.6 F, with a normal low of 59.5 F. Since 1894, the high temperature has been 80 F or higher 37% of the time (48 out of 130 years) and at least 90 F just over 6% of the time (eight years). The low temperature has been 55 F or lower 43% of the time (56 years), and 45 F or lower just 3% of the time (4 years). Measurable rainfall has occurred on just under a third of all years historically (42 out of 130 years), with amounts of a quarter-inch or more occurring about nine percent of the time (12 years).
September 5, 2023