While September continued the very warm pace in 2024, the persistent rain spigot that has been on in central Minnesota through early August was closed to a large degree in September.

Temperature Summary

The average September temperature at the St. Cloud Regional Airport was 67.1 degrees, 7.6 degrees warmer than average. This broke the old record for September, which was 66.5 degrees in 1931. Unlike much of the summer, the very warm temperatures were fueled by persistently warm high temperatures. The average high temperature of 80.5 degrees was the warmest September high on record, and was warmer than either the June (78.0 degrees) or August (80.3 degrees) average highs. The low temperatures were quite warm statewide during the middle third of the month, when dew points were persistently in the noticeable upper 50's or uncomfortable lower 60's (see blue line on the 30-day temperature and moisture St. Cloud chart from MesoWest). The average low of 53.6 degrees was the 5th warmest September low in St. Cloud records.

While St. Cloud didn't have any 90-degree highs in September, there was a consistent parade of highs in the 80's. 19 of the 30 September days had a high of at least 80 degrees (September average is 6 days), the second highest total of 80-degree highs in St. Cloud records. Only 1908 (21) had more 80-degree highs in September (see table below). So far in 2024, St. Cloud has seen 81 highs of at least 80 degrees, the 13th highest total on record. The most was 99 days, set in 1900. This is despite St. Cloud having a below-average number of 90-degree highs (6, below the average of 11.4 days).

The warmth was so consistent that St. Cloud never had a high cooler than 70 degrees in September (70 on the 22nd was the coolest high). This is the first September without a high in the 60's or cooler since St. Cloud temperature records began in 1881.

St. Cloud managed to set 4 warm temperature records in September. The hottest days, 88 degrees on September 16 and 17, fell short of the daily records. However, high temperature records were set on September 28 (87 degree high) and tied on September 29 (85 degree high). Still, last year broke more records as the temperature topped 90 degrees on both October 1 and 2. On September 19, the temperature never fell below 69 degrees, breaking a record warm low.

Despite a mixed bag of summers, St. Cloud has enjoyed a series of warm Septembers. Including 2024, 11 of the past 12 Septembers have been warmer than average, including 2015 (tied for 6th warmest).

The warmth has persisted through the year (and going back through May 2023). The first 9 months of 2024 had an average temperature of 52.1 degrees, 0.1 degree short of the 2012 record (see table below). Last year at this time, I noted the heat of the warm season (May-September average was 68.1 degrees, the 3rd warmest on record (see table below).

The persistent warmth since last summer was aided by the El Nino (unusual warm current of water off the Central American and South American Pacific coast) episode. Even though El Nino faded over the summer, ocean temperatures were very warm, so warmth this summer wasn't surpirsing. However, the table below shows that all the warmest Jan-Septs have occurred since 1998, the time period of dramatic temperature increases in the cool season. Of the years with the warmest January through September, only 2021 also ranked among the top 10 warmest summers. In the St. Cloud seasonal temperature rankings, 4 of the top 10 warmest falls, 4 of the top 10 warmest springs, and 5 of the top 10 warmest winters have occurred since 1998. This is consistent with the predictions of global warming (warming would be largest in northern latitudes and at the cooler times of year).

If we get only average temperatures during the last three months of the year, the 2024 annual temperature average would be 46.9 degrees, which would rank as the 3rd warmest year in St. Cloud history behind only 1931 and 2012. We'd need a major outbreak of cold weather to keep 2024 out of the 10 warmest years.

Driest September Reverses Earlier Trend

The drier trend seen in northern Minnesota during the middle and late summer spread throughout Minnesota in September. Only 0.35 inch fell in September at the St. Cloud Regional Airport. This was 2.66 inches below the September average, making September 2024 the 3rd driest September in St. Cloud records. Using the NWS Water Prediction Service Minnesota maps, you can see that central Minnesota was still wet going back to July (see 90 days ending September 30; 10-15 inches central Minnesota (yellow), but less than 8 inches north and south), and in August, although much of the rain was concentrated early in the month (see 60 days ending September 30; less than 6 inches of rain (light green or blue), except Melrose and Paynesville east to Pine City). But, in September, only extreme northern Minnesota got well above average rainfall with merely average rainfall east of St. Cloud and Little Falls (see 30 days ending September 30; less than half an inch (blue) except pockets east of Lake Mille Lacs and northern Minnesota).

This wet period began last December, so the total December through September precipitation is still 32.81 inches, 8.30 inches above the 24.51 inches average. St. Cloud's rank among the wettest December through September dropped to 8th wettest (it was ranked 2nd wettest December-August). Similarly, the cumulative precipitation in 2024 (January through September) stands at 29.46 inches, which is 5.83 inches above the 23.63 inches average. The rank for Jan-Sept dropped to 14th wettest (after 5th wettest January-August).

Despite the general dryness, a wave of strong thunderstorms hit northern Minnesota, dropping large hail and even a tornado in Cotton (see September 19: NE MN Hail, Cotton Tornado summary from NWS Duluth.

    September 2024 Statistics

 Last Updated: October 1, 2024