St. Cloud, MN Weather Forecast

Auto Pollution, Rather Than Wildfire Smoke The Problem

So far during May, Minnesota has seen some air quality issues during the middle of the month, thanks to the smoke from a few wildfires in northern Minnesota. However, the early fire season in the Canadian Prairie Provinces has produced far fewer fires than at a similar time last year (change date to May 29, 2025, turn off Fire Weather Index, and turn on reported wildfires on the Environment Canada interactive wildfire map).

However, the other potential source of air pollution happens on sunny and hot days. Then, the sun works on vehicle exhaust to produce high levels of ozone. This gets worse when the winds are light (less of a chance to bring in better air quality) and there is a pocket of unusually warm air in the middle atmosphere (keeping the lower layers from mixing with the middle atmosphere, moving some of the ozone away from the ground). The ozone level rose to moderate in the Twin Cities Cities yesterday afternoon (set date to May 28, pollution type to ozone, location to Minneapolis, Shakopee, or Blaine on the Minnesota Pollution Control Agency's past air quality graph). This problem eased a bit overnight, since there is less traffic, and we've had a persistent southeast breeze (see NWS Aviation Weather Center METAR map).

Twin Cities Air Quality Alert Friday All Afternoon into Early Evening

Today, high temperatures are expected to be a bit warmer, increasing the ozone production. The Minnesota Pollution Control Agency has issued an air quality alert for the seven counties in the Twin Cities Metro Area. 

In northern Minnesota, the elevated fire danger will continue due to hot temperatures.

Warmest Today, Slightly Cooler and Much Drier Weekend

Otherwise, the forecast for the upcoming weekend will feature warm temperatures, modest humidity, and only a slight chance for showers and thunderstorms, with the best chance in southwestern Minnesota (see Days 1-3 of the NWS WPC quantitative precipitation forecast). After today, the high pressure area (clear sky at the center of the clockwise rotation from the eastern Dakotas into Manitoba and Minnesota on the College of DuPage clean infrared satellite loop) will circulate even more air from Ontario and Manitoba through the northern Great Lakes and Wisconsin into Minnesota.

Today will be the hottest and most humid day of the weekend, since dew points have returned to the middle 50's in central Minnesota with some southern Minnesota stations reporting an uncomfortable 60 degree dew point (see NWS Aviation Weather Center METAR map). However, the continued flow from the east and northeast will push slightly cooler and considerably drier air (see green areas on the UCAR hourly dew point chart) back into eastern and central Minnesota over the weekend.

Highs today will return to the upper 80's and perhaps reach 90, but highs will fall back to the middle 80's tomorrow and near 80 on Sunday. And, we should see the return of dew points in the lower 50's and perhaps even the 40's over the weekend. As the showers and thunderstorms (see College of DuPage north central US radar loop) get shunted north to northwestward into the Dakotas and Montana over the weekend, there may be times when we have more middle and high clouds (see a few caught up in the northwest to southeast flow over Minnesota this morning on the  College of DuPage clean infrared satellite loop), so low temperatures may not drop out of the 50's.

Be Ready in West Central and Southwest Minnesota For a Scattered Storm

While western Minnesota will have better than a 1 in 3 shot at showers and thunderstorms each weekend day, I rate the central and eastern Minnesota chance at no better than 1 in 5 (note that central and eastern Minnesota are not even in the green thunderstorm chance area in Days 1, 2, or 3 of the NWS Storm Prediction Center convective outlooks).

Will We See Significant Rain Next Week?

The long-range forecast weakens the high to our north, which will allow Pacific weather systems to begin moving west-to-east near the Canadian border. This would allow the persistent thunderstorms expected in the Northern Plains and northern Rockies to move eastward, but the forecasts vary on when that may happen. So, I am uncertain about the thunderstorm chances from Wednesday into Friday, but there could be the potential for some parts of Minnesota picking up important rainfall.

May Statistics Show Prolonged Dryness Continuing

As I begin the process of composing the May and meteorological spring (March 1-May 31) St. Cloud weather summary, the need for rain is reinforced. Most of the northern two-thirds of Minnesota has picked up less than 2 inches of rain during the past 30 days (set NWS Water Prediction Center Minnesota map to yesterday's date and last 30 days period). If St. Cloud misses rain over the next 3 days, we will end up with only 1.21 inches of May rainfall, making this the 13th driest out of 134 Mays in St. Cloud records. While including the snowfall in total precipitation is misleading for ground water (the snow usually melts before the ground thaws), the total precipitation since the start of our dry period last August is only 13.38 inches, 6.10 inches below average and the 10th lowest August through May precipitation in St. Cloud records.