A series of small disturbances interacting with a very humid air mass led to multiple bouts of thunderstorms and heavy rain, affecting different parts of Minnesota from Monday July 21st through very early on Thursday July 24rd, 2025.
Although the state experienced multiple bouts of storms and rain during this period, each affecting some areas while missing others, the general pattern was for the heaviest rain to start in the north, and gradually work southward over the three days. The activity formed night and day.
By the end of the three days, all but southwestern Minnesota had received at least a half-inch of rain, and most areas had between a half-inch and 1.5 inches. About 40% of the state had 1.5 to three inches of rain, and there were small areas of 3+ inches around Bemidji, Grand Rapids, Hibbing, Grand Marais, St. Cloud, Mankato, Northfield, and in the two tiers of counties in extreme south-central Minnesota. The highest total rainfall was in the Mankato area, where numerous CoCoRaHS observers reported over five inches of rain, almost all of which fell during the evening of the 23rd. The rains flooded roads and basements in and near Mankato, and earlier in Hibbing.
The humidity fueling this prolonged wet episode was quite deep. The total "precipitable water" measured by weather balloons launched from Chanhassen was generally between 1.65 and 1.9 inches, well above the 90th percentile (meaning more water in the air than at least 90% of other observations), and near some daily record levels. We could feel the humidity too, with dew point temperatures generally from the upper 60s to mid-70s F.
Posted July 24, 2025
KAB