St. Cloud, MN Weather Forecast

September Wetter... 

As the calendar turns to October, we finished a September which helped to ease the persistently dry conditions. The St. Cloud Sky Central Airport picked up 4.36 inches, the most monthly rainfall since July 2025 and only the third of the past 12 Septembers with near average rainfall or more. And, north central and southern Minnesota had over 5 inches (red or dark red when you set NWS Water Prediction Service Minnesota rainfall map to yesterday's date, and last 30 days time period). There were some pockets of southern Minnesota with over 10 inches of rain (magenta). Even St. Cloud State University had 4.79 inches of rain. 

The new US Drought Monitor, which will miss the rain that fell on Tuesday (set NWS Water Prediction Service Minnesota rainfall map to yesterday's date and 1 day), will show considerable improvement in the northern Minnesota dryness (set comparison dates to September 29 and September 1). Still, there is more ground to make up. The rainfall deficit since August of 2025 is still 9.77 inches (25.73 inches actual, 35.50 inches average). While the grass is quite green, you can still see all the dry spots in the Mississippi River as the stream flow increase below the St. Cloud Dam has been modest (click on green box on the NWS Water Prediction Service river flow chart). There is less red and more orange on the Minnesota DNR cooperative stream gaging map, when you click on the current weekly stream flow report.

...And Warm (91st 80-degree high of year yesterday)

On the other hand, the lingering warmth yesterday produced some highs near or even above 80 degrees yesterday (see yesterday's 4 PM CDT NWS WPC North America zoom-in map), including St. Cloud (see NWS: last 72 hours of St. Cloud observations). That was more than 15 degrees warmer than average and the 11th high of at least 80 degrees in September (10 of the first 11 days of the month and yesterday). That makes 91 days with a high of at least 80 this warm season (on the NWS Twin Cities NOAA Data site, click on St. Cloud area, monthly summarized data, starting date to 'por,' period of record, variable to max temperature, summary to number of days, and threshold to >= 80). That's the third highest total of 80-degree days, trailing only 1900 (99 days) and 1988 (92 days).

That brought the September 2026 average temperature to 63.8 degrees, 4.0 degrees above average. This September ranked as the 14th warmest on record, and only 0.8 degrees short of last September, which ranked as the 9th warmest September. 

Seasonably Cool and Dry Beginning Today...

However, conditions will change drastically today. The blooming cloud area ahead of the Rockies storm (see College of DuPage North America clean infrared satellite loop) pushed into southern and central Minnesota overnight, but the rain remains no closer than the Iowa border (see College of DuPage north central US radar). However, the cooler (highs in the 60's and some 50's on the yesterday's 4 PM CDT NWS WPC North America zoom-in map) and drier (dew points in the 40's and 30's, blue or white on the UCAR hourly dew point chart) air in the Canadian Prairie Provinces will push in today and persist through next Monday. Highs will be in the 60's in general, but could only reach about 60 degrees on Friday and Sunday.

...With Scattered Frost Threat Tonight...

The potential for the first frost of the year appears better than it looked early, with at least a close brush towards scattered frost in parts of central Minnesota Thursday night into Friday and still the greater chance for frost Sunday night into Monday. The breeze shown for tonight is a bit lighter in recent forecasts, so I'm bringing back the potential for lows in the 30's and scattered cold spots could dip to the 30-32 degree range early tomorrow. The potential for frost and freeze will be more widespread in northern Minnesota (NWS frost and freeze advisories are for tonight).

...Better Frost Threat Sunday Night?

The Sunday night air mass will be from the northern Canadian Prairie Provinces or even the Northwest Territories, so it will be even drier, supporting dew points in the 20's. There is still a question of wind, but the breeze looks like it will calm the second half of Sunday night. At 4 days out, I'll say there's a good chance for frost in the low-lying areas and areas that are sheltered from a northwest breeze on Monday morning, but I'm not sure about widespread frost yet. However, frost will be common in northern and north central Minnesota with a hard freeze (temperature of 28 or colder) quite possible.

The change in air mass means that any front coming through Minnesota will only produce a small chance of rain. That potential is highest on Saturday afternoon and early evening (1 chance in 3; see Days 2-3 of the NWS WPC quantitative precipitation forecast) with little chance otherwise through Monday.

Alternating Between Warmer and Cooler Air Next Week

Temperatures will likely rebound a bit as we get into next week, but we will be close to the northern storm track during that time. That means rapid temperature changes that are hard to forecast this far in advance. I'll guess that the temperature will generally stay within 10 degrees of the early October average. The air will be dry, so the threat of rain with any change of air mass will be small.