September Part Mid-July, Part Halloween While Dodging Rain

September 2018 Saint Cloud Weather Summary

September 2018 lived up to nearly no expectations in St. Cloud. The first half of the month was more typical of mid-summer than the first 2 weeks of fall, then there was a sudden reversal during the second half of the month. The net result was an average September temperature of 60.4 degrees at the St. Cloud Regional Airport. That total was 1.8 degrees warmer than average

Two surges of warm and humid air kept lows in the 60's on two of the first 4 days of the month. Later on, St. Cloud posted a week of high temperatures no cooler than 83 degrees with 5 straight lows in the 60's. On September 15 and 16, St. Cloud temperatures broke 90 degrees. While there were no temperature records set, only 6 Septembers since 1984 have had a 90-degree high. These were also the latest 90-degree highs recorded in St. Cloud since the temperature reached 92 on September 19, 1998. The average temperature for the first 16 days of September was 68.0 degrees (average high 79.1, average low 56.9), which would have ranked as the warmest September in St. Cloud records if it kept up.

Then, the weather changed drastically as a wet weather system dumped rain and brought in significantly cooler air to the last 10 days of the month. High temperatures only reached 70 degrees on 2 of the 13 days of the month with the high failing to reach 45 degrees on a Halloween-ish September 29. That 44-degree high was one degree off the record cold high for the date. On the evening of September 28, the temperature fell back into the 20's, producing the first frost and readings bottomed out at 27 degrees on September 29. The September 28 date was within two days of the average first frost date. This did mark a hard freeze at the St. Cloud Airport and was 6 days earlier than the average first 28 degree low. Still, the short duration of the temperature below 28 allowed the city of St. Cloud to dodge a hard freeze.

The average temperature for the last 14 days of September was 51.7 degrees (average high 60.7, average low 42.7). If that had kept up all month, it would have tied 1993 for the second coolest September.

Since the last frost of the spring was on April 28, the growing season was 152 days long, among the longest 20 percent of growing seasons.

St. Cloud rainfall was well below average, but that was misleading as well. The St. Cloud Airport got 2.17 inches of rain, 1.29 inch below average. This made the St. Cloud growing season rainfall (April 1-September 30) 18.47 inches, 1.78 inch below average. The annual precipitation was 22.04 inch, 1.00 inch below average. However, there were over 4 inches of rain near Rice and Holdingford. Much heavier totals (mostly 5 inches of more) covered an area south of Montevideo, Benson, Willmar, Atwater, Monticello and Elk River. Much of this heavier rain fell between September 3 and 5 and again on September 20. That day, there was also an outbreak of 16 tornadoes in south central and southeastern Minnesota.

    September 2018 Statistics