Most of Minnesota experienced a significant warm spell from late September in to early October 2025, but in western parts of the state the prolonged streak of consecutive, summer-like days occurred more than three weeks later than than any comparable period on record.
On first glance, it may be hard to differentiate this spell of extremely warm weather from other recent outstandingly warm early fall periods. After all, 2024 had the warmest September and warmest September-through-October in 130 years of record, and September 2023 had an intense Labor Day heat wave, followed by another one a full month later that caused outright cancellation of the Twin Cities Marathon. One could be forgiven for not recognizing anything astonishing about 2025's encounter with autumn heat.
The hot period beginning in late September and ending in early October 2025 was different, however. It wasn't simply the magnitude, although the final heat barrage on October 4th did break a slew of daily and other records. What made this one extraordinary was the duration of the warmth so late in the season, especially in western Minnesota.
For instance, at Milan, which is just off Highway 7 in Chippewa County and one of Minnesota's premier climate locations, the maximum daily temperature reached 85 F or higher on 11 straight days, from September 25 through October 5th. To put this feat in perspective, consider that with temperature records back to the 1890s, Milan has never before recorded the final day of a 10-day streak of 85 F temperatures after September 13th. In other words, this streak was more than three weeks later than the next-latest one on record. Additionally, the streak at Milan was the longest in all of 2025, meaning that even the heart of summer did not produce a streak of daily high temperatures like this one. The only contender was an eight-day streak, from June 28th to July 5th.
This warm spell began with a "dry heat," featuring sunny skies and low humidity. As a result, the first several nights were not as abnormally warm as the days, with low temperatures only 5-10 degrees F above normal, as opposed to 15-25 F above normal for the high temperatures. More moisture moved into the region around September 30, resulting in low temperature that were 10-20 degrees above normal, making it abnormally warm both day and night.
This hot spell helped cement yet another warm September, and contributed to the ongoing trend of summer weather extending deeper into the fall.
October 24, 2025
KAB