St. Cloud, MN Weather Forecast

Natural Air Conditioning 

The cooler and drier air took hold yesterday. High temperatures only climbed into the upper 70's (see yesterday's 4 PM NWS WPC North America zoom-in map) for the first time since July 7-8. This morning will likely be the coolest morning we've seen so far this month as early morning temperatures ranged from the middle 50's to even the 40's not far to our north (see latest NWS Aviation Weather Center METAR map). A middle 50's low in St. Cloud will be the first one since June 24-26.

The cooler weather will continue today and tomorrow. Highs will be in the 70's to perhaps near 80 again today. We will have another shot at a low well down in the 50's tonight, then highs will return to the middle 80's tomorrow, but the dew points will continue to be in the 40's and 50's (green on the UCAR hourly dew point chart).

Heat Building in the Rockies: 90's Return for Weekend Here

The high pressure carrying the heat is now in New Mexico and Colorado (see clockwise rotation on the College of DuPage North America mid-level water vapor loop). The 90's in Idaho, western Colorado, and Utah (see yesterday's 4 PM NWS WPC North America zoom-in map) will spread to the Northern Rockies today and to eastern Montana and the western Dakotas by tomorrow (see eastward movement of red on the NWS Heat Risk). That heat will build eastward behind a warm front due to pass Minnesota Friday night. Then, much of Minnesota will have the potential for highs in the 90's with dew points back in the uncomfortable 60's over the weekend. 

Smoke and Fire Issues

The main weather risk this week will be: 1) whether the smoke in the Canadian Prairie Provinces (see EPA fire and smoke map) reaches central Minnesota and, 2) will more fires begin and the existing fires (see current Minnesota wildfires from Western Fire Chiefs US fire map) spread into more of Minnesota.

Any day of warm temperatures, low humidity, and windy conditions will risk the development of more wildfires. Today won't be as windy as yesterday (wind gusts of 25-30 MPH yesterday; see NWS: last 72 hours of St. Cloud observations), so the fire danger should be a bit lower. The fire danger should climb in the warmer and windier conditions Friday and through the weekend.

Our air is forecast to come from central Manitoba, where there is more middle-level haze, as we had yesterday, from the wildfire smoke (see shaded areas on the EPA fire and smoke map). That mid-level smoke hasn't affected the ground AQI in Minnesota yet. The low-level smoke has pushed the air quality index down to the orange levels from Saskatchewan into North Dakota (see this view of the EPA fire and smoke map). There is a small chance that some of this smoke gets into parts of Minnesota (note the forecast yellow levels across Minnesota tomorrow and Friday). And, the lighter winds today and tomorrow could allow pockets of serious air quality issues due to the current wildfires. The hotter weather over the weekend will come on south winds, so the smoke won't be a factor.

Only Decent Rain Chance Friday Night

Our best chance for showers and thunderstorms during the rest of the week will come as the warm front pushes through in central Minnesota. That will be Friday night. The chance won't be that great (I have a 30% shower chance in central Minnesota) and will be the best in northern Minnesota (see Days 2-3 of the NWS WPC quantitative precipitation forecast). The main severe weather chance as well as the chance for significant rain will concentrate in northern Minnesota.

There could be more showers and thunderstorms from late in the weekend into early next week. The computer forecasts are trying to bring some cooler air into Ontario. That could drive a cold front through Minnesota at some point, but the computer forecasts disagree about when any front would pass. So, the thunderstorm is uncertain.