Preliminary Climate Summary for September 2025:
Despite a cooler than normal start to the month, this September will end up warmer than normal across virtually all of Minnesota. Average monthly temperatures will range from 2°F to 5°F above normal, with dozens of locations reporting at least one 90°F daily maximum temperature. Extremes for the state ranged from 94°F at Worthington (Nobles County), Fairmont (Martin County), and Sherburn (Martin County) on the 13th to just 29°F at Brimson (St Louis County), Hibbing (St Louis County) and International Falls (Koochiching County), all during the first 10 days of the month.Rainfall was mixed during September, with parts of northeastern and southeastern Minnesota receiving the most rainfall. With the forecast calling for dry weather through the end of the month next Tuesday, the current rainfall totals from around the state will remain the same. About a quarter of the climate observers report over 3 inches of rain for the month (above normal), and a few eastern Minnesota communities report over 5 inches. Within the state climate station network, there were at least two dozen daily rainfall records set, mostly from mid-month thunderstorms. Among these records were:
3.28 inches at Rochester on the 22nd
2.85 inches at Hastings Dam on the 22nd
2.04 inches at Artichoke Lake on the 19th
2.25 inches at Brainerd on the 13th
1.97 inches at Brimson on the 9th
Crop harvesting activity has picked up, especially for soybeans, while some farmers are also harvesting corn. Conditions are expected to remain favorable for crop harvesting through the first week or two of October as well. Don’t forget it is apple season in Minnesota as well.
Weekly Weather Potpourri:
Typhoon Ragasa (mentioned in last week’s WeatherTalk Blog) hit the south China coast this week with high winds, large waves, and drenching rains. According to the BBC Typhoon Ragasa was one of the strongest storms of the season so far, generating winds gusts over 100 mph and high seas. Coastal residents were relatively well prepared for the storm, but damage assessments are still being made.The Weather Underground reported that the first significant snowfall occurred this week (September 23) in the Colorado Rockies. Reports of 6 to 8 inches we re common at elevations of 8,000 to 10,000 feet. To early to gear up for the ski season, but perhaps a sign of early winter abundant snowfall?
A new study published in the journal Nature called “Wildfire smoke exposure and mortality burden in the U.S. under climate change” concludes that over the next 50 years wildfire smoke will provoke a huge spike in health risk and deaths on an annual basis. The authors conclude that “the health impacts of climate-driven wildfire smoke could be among the most important and costly consequences of a warming climate in the US.”
MPR listener question:
As we enter October next week, do you see any signs of more widespread frosts in southern Minnesota? Our vegetable garden is still giving us plenty of produce and we hope it lasts a while longer.Answer:
No, I don’t. It appears that the first two weeks of October will definitely bring warmer than normal temperatures to Minnesota, so frosts of any kind will be relatively absent. There may be a stray frost or two, but only in northern areas of the state.Twin Cities Almanac for September 26th:
The average MSP high temperature for this date is 69 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 50 degrees F (plus or minus 7 degrees F standard deviation).MSP Local Records for September 26th:
MSP records for this date: highest daily maximum temperature of 87 degrees F in 1923; lowest daily maximum temperature of 41 degrees F in 1942; lowest daily minimum temperature of 27 degrees F in 1965; highest daily minimum temperature of 64 degrees F in 1998; and record precipitation of 1.81 inches in 1930. There was a record snowfall of 1.7 inches in 1942.
Average dew point for September 26th is 46°F; the maximum dew point on this date is 70°F in 1986 and the minimum dew point on this date is 20 degrees F in 1965.
All-time state records for September 26th:
The state record high temperature for this date is 93 degrees F at Madison (Lac Qui Parle County) and at Redwood Falls (Redwood County) in 1974. The state record low temperature for this date is 11 degrees F at Crookston (Polk County) in 1893. The state record precipitation for this date is 4.40 inches at Coon Rapids (Anoka County) in 2023. A record 7.5 inches of snow fell at Long Prairie (Todd County) on this date in 1942.
Past Weather:
September 26 of 1942 is a climatic benchmark of sorts in that it marks the earliest fall occurrence of a widespread and significant snowfall in Minnesota. Though MSP officially recorded 1.7 inches (most of which fell from 8 pm on the 25th to 8 am on the 26th), many of the city parks reported 2 or more inches. Much of this melted during the day on the 26th, but the heavy wet snow damaged trees and shrubs which had not lost their leaves. Elsewhere around the state the snow was heavier yet and required some shoveling. Bird Island and Long Priarie both received over 7 inches of snow, while Detroit Lakes and Willmar reported 6 inches.
September 26 of 1965 was one of the coldest in state history, with frosts reported in almost all corners of the state except Winona. Morning low temperature were in the teens and twenties F across central and northern Minnesota. The afternoon high at Cass Lake only reached 35°F, a record cold high temperature for the date. It brought an abrupt end to the gardening season.
The warmest ever September 26th was in 1974 when most areas of the state reported daytime high temperatures 80°F to 93°F. After a morning low of 41°F, the temperature at Milan (Chippewa County) rose 51°F to a high of 92°F by 4pm.
Outlook:
Continued very warm and sunny through the weekend and much of next week. The air will feel drier, with less humidity as well. Little chance of rain until next Thursday when some areas of the north may see showers.
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