St. Cloud, MN Weather Forecast

Latest Warnings for Heat, Air Quality, and Fire

The heat, fire, and air quality issues continue in Minnesota

1. Heat and Humidity
   1. Extreme Heat Warning (heat indices in the 100's, plus streak of uncomfortable low temperatures) continues in central Minnesota (Brainerd through Mankato) through 7 PM Thursday
   2. Heat advisory (heat indices 95-100)
      1. northwestern Minnesota (including Fergus Falls, Detroit Lakes, Fargo-Moorhead, Wadena, Ortonville)
      2. northeastern Minnesota (including Duluth and Grand Rapids)
      3. southeastern Minnesota (including Rochester, Winona, Albert Lea, LaCrosse)
   3. Latest reports
      1. Table including heat index when 88 or higher.
      2. Map of temperatures and dew points
2. Air Quality Alert through Friday 11 AM
   1. Northeastern Minnesota:  Hazardous enough to affect everyone
   2. Moorhead to International Falls through the central lakes into St. Cloud, Twin Cities, and the St. Croix Valley, and Mississippi River to Winona: will cause some symptoms for everyone
   3. Latest reports
      1. north to northeast winds
      2. Air quality in northeastern Minnesota and Ontario
3. Fire Danger
   1. High to very fire danger in northern Minnesota (perhaps red flag warning in northeastern Minnesota?) 

Yesterday Made This Week an Official Heat Wave 

Yesterday, the temperatures were warmer in central Minnesota, while they were a good 10-20 degrees cooler along the Canadian border (see 20Z-22Z, 4-6 PM, on the NWS Aviation Weather Center METAR map). The hottest temperature I saw was 96 degrees in Pine River. St. Cloud got one degree higher than Monday to 93 degrees, the hottest temperature of the summer. That was the third straight day with a 90-plus high, so this week now qualifies as a heat wave. St. Cloud's previous heat wave was July 25-28, 2023.

The dew points climbed into the lower 70's, so the heat indices got into the lower 100's with a few middle 100's in places like Fergus Falls (see 3-5 PM on the NWS Minnesota hourly round-up). St. Cloud's highest heat index was 102 (see NWS: last 72 hours of St. Cloud temperatures). 

The reason for both the cooler northern Minnesota temperatures and the higher central Minnesota dew points was the advance of a weak cold front (see yesterday's 4 PM CDT NWS WPC North America zoom-in map). To the north of the front, slightly cooler and drier air (dew points in the 60's and even some 50's) from the Canadian Prairie Provinces moved in. To the south, extra moisture was trapped, so dew points were stuck in the low to even middle 70's. That front is still hung up near the Brainerd and Detroit Lakes early this morning, so temperatures have remained in the 70's to the south (see latest NWS Aviation Weather Center METAR map).

Forecast: Still Very Warm to Hot Through Friday, Cooler and Drier Saturday (Air Quality Issues May Continue) 

Over the next 5 days, that front will wobble north and south, thanks to a series of weak storm systems moving along the front. We will see changes in our temperatures and humidity due to those changes. Temperatures will also be lowered somewhat due to the haze from the wildfire smoke. Today and tomorrow are likely to be a little cooler than the past three days. So, we could continue the heat wave with highs in the lower 90's, but there is a chance we end up short of the mark. Lows will likely remain near 70, perhaps getting into the upper 60's to our north.

On Friday, the front will move back to the north. That will allow the hottest back and might push the wildfire smoke northward. So, I have the highs back between 90 and 95 with some chance of heat indices around 100 again. And, it will be breezier, so the danger of more wildfires will climb again.

A stronger cold front is due to pass on Friday night. That will at least allow a decent surge of Canadian air for Saturday and early Sunday. Lows will be in the 60's Friday night and could get to 60 on Saturday night. Highs will be in the middle to upper 80's.

A brief surge of hotter air will push in during Sunday. However, I expect a fair amount of clouds, so we might brush 90 degrees, but temperatures could also remain in the 80's.

Now, the computer forecasts are consistently showing a low from Alaska pushing into the Canadian Prairies by Sunday and into the Great Lakes on Monday. If that happens, we could get a longer break from the heat and humidity. However, that is a major shift from the computer runs of the past two days. So, I'm not going to count on highs in the 80's or even 70's for Monday and Tuesday yet. Any shift to strong northwest flow could bring wildfire smoke from the Northwest Territories, Nunavut, and the northern Canadian Prairie Provinces into Minnesota, but I can't forecast whether that smoke would be near the ground or at high levels. 

Some Rain Chances

Note that there was one of those overnight blobs of thunderstorms in Montana last night (see College of DuPage continental US clean infrared satellite loop), thanks to some of the moisture from northern Mexico creeping through the Rockies (see College of DuPage North America mid-level water vapor loop). When the front passes in either direction (northward early Friday, southward Friday night), there will be a chance of some scattered showers and thunderstorms. The best chances will be Thursday night when the next surge of the hot air begins, Friday night when the cold front comes back, and perhaps Sunday if the stronger front pushes through. But, I don't give a chance better 1 in 3 at this point (see NWS WPC quantitative precipitation forecast).