Friday, August 8, 2025  2:50 AM 

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

Another Round of Heat, Storms, and Smoke (Hit the Send Button on Those Complaints!)

The three issues that Minnesotans have been complaining about are all in the forecast over the next three days. Details one by one:

1. Heat and Humidity

The National Weather Service has a heat advisory for the Minneapolis-St. Paul Metropolitan area today from noon through 10 PM. The Hinckley area is also under the heat advisory. But, the rest of southern and central Minnesota will have conditions nearly as oppressive today.

The same oppressive humidity (dew points in the low to even middle 70's; see UCAR hourly dew point chart) will even get worse (dew points more likely in the middle 70's today) since the huge mesoscale convective complex (large red blob of thunderstorms on the College of DuPage clean infrared satellite loop) will slide just to the north of central Minnesota (1 in 3 chance for a morning thunderstorm). That will pump up the dew points. The leftover clouds from these storms should push eastward by midday, so highs will climb to near 90 or a bit above, producing heat indices between 95 and 100 (yesterday, St. Cloud reached a 91 degree heat index). That's after a sweltering night with temperatures in the 70's (see NWS Aviation Weather Center METAR map). You can track the hourly temperatures, dew points, and heat indices on the NWS Minnesota hourly weather round-up.

Tonight, the sweltering conditions will continue....until the thunderstorm threat develops.

2. Thunderstorms

1. This morning for northern and parts of central Minnesota. That large thunderstorm blob covering North Dakota and nearby Canada (see College of DuPage clean infrared satellite loop) will push east and northeastward (see College of DuPage north central US radar). The southern-most portion of these storms are moving more west-to-east, so there will certainly be storms this morning in northern Minnesota at least from the Canadian border to Hwy. 210 and there is a chance some of these storms could brush St. Cloud. These storms have a history of producing straight-line damaging winds (there are fewer reports in eastern ND, but there are few people awake to observe these storms; assume that these storms are still capable of producing straight-line wind damage, perhaps some large hail, and heavy rainfall (see Day 2 of the NWS WPC Excessive Rainfall Forecast this morning).
2. This evening into early morning Saturday: most of Minnesota. The low pressure system in British Columbia (see College of DuPage mid-troposphere water vapor loop) will reach Saskatchewan tonight, pushing the cold front into Minnesota. That system will lift the extremely soupy air, producing another thunderstorm outbreak. Severe weather (afternoon storms could produce any form of severe weather, most likely near the Dakotas-Minnesota border; from mid-evening on, the most likely severe weather will be straight-line damaging winds). There is also a chance for heavy rainfall, producing potential flooding.

3. Smoke

Behind the cold front, our air source will be Montana for much of tomorrow. By Saturday afternoon, the low in southern Canada will circulate Canadian Prairies air. The air quality in Saskatchewan and Manitoba is really bad right now (see EPA fire and smoke map) with red air quality in central Saskatchewan and even purple air quality in southern Manitoba. The overnight storms are producing rain in southern Manitoba and Saskatchewan (note the better air quality south of Saskatoon), so some of the worst air quality may be moderated before that air gets here. An air quality alert is likely over Minnesota beginning late tomorrow or tomorrow night and spreading throughout Minnesota by Sunday.

Otherwise, the new air mass moving in beginning tomorrow will produce warm temperatures, but they won't be as high as today. And, the humidity will ease from stifling levels today to merely uncomfortable tomorrow and marginally drier Sunday through Tuesday. So, expect highs in the 80's and lows near 60. The chance of rain will diminishing after tomorrow morning, but there may be a stray shower Sunday. And, the chances for rain will remain frequent but uncertain early next week.

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "The Bugs Are Waiting for Me to Mow the Lawn"

Friday 8/8/2025: A chance for an early shower or thunderstorm. Otherwise, more hazy sunshine with hot temperatures and oppressive humidity. Low level air pollution possible. High: between 87 and 93 (record warm high: 96 in 1947). Winds: SE 10-25 MPH with higher gusts. Chance of measurable rainfall: 30%.

Friday Night: Breezy, warm, and oppressively humid. A good chance for showers and thunderstorms, especially during the early morning hours. Severe weather may be possible. Low: between 66 and 72. Winds: SW 8-15 MPH with higher gusts in storms. Chance of measurable rainfall: 70%.

Saturday 8/9/2025: A good chance for morning showers and thunderstorms, then becoming sunny and breezy, but not quite as hot with uncomfortable humidity. High: between 82 and 87. Winds: SW 10-20 MPH. Chance of measurable rainfall: 60% during the morning, 10% during the afternoon.

Confidence Level: "Extra Bugs Will Come From Every Home on the Block to Hover Around My Head"

Saturday Night: Partly cloudy during the evening, mostly cloudy late with a slight chance of a sprinkle towards morning. Slightly cooler with noticeable to uncomfortable humidity. Low: between 60 and 65. Winds: S 5-10 MPH. Chance of measurable rainfall: 20%.

Sunday 8/10/2025: Mixed clouds and sun, breezy, warm, and uncomfortably humid. A slight chance for a shower. Smoke issues likely. High: between 80 and 85. Winds: W 10-20 MPH. Chance of measurable rainfall: 20%.

Sunday Night: Clear with light winds. A chance for fog towards morning. Cooler and not quite as humid. Poor air quality. Low: between 58 and 63. Winds: SW 5 MPH. Chance of measurable rainfall: 10%.

Monday 8/11/2025: Partly sunny, breezy, and seasonably warm again. A slight chance for a late day shower or thunderstorm. Noticeable to uncomfortable humidity. Smoke issues continue. High: between 80 and 85. Winds: SW 8-15 MPH. Chance of measurable rainfall: 20%.

Confidence Level: "Enough Bugs Will Fly into My Mouth to Throw Off My Diet"

Monday Night: Partly clear with a chance of a shower or thunderstorm. Still fairly warm. Low: between 60 and 65. Winds: SW 5 MPH. Chance of measurable rainfall: 30%.

Tuesday 8/12/2025: Continued hazy sunshine, warm and uncomfortably humid. Uncertain chances for a shower or thunderstorm. Smoke? High: between 80 and 85. Winds: SW 5-15 MPH. Chance of measurable rainfall: 30%.

Extended: Continued frequent chances for rainfall early next week??? Uncertain temperatures, but likely humid???

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 7 Friday and Friday night, 4 Saturday night and Sunday, 5 Sunday night and Monday, 2 Monday night and Tuesday.

Yesterday's High: 86°F; Overnight Low (through 3 AM Friday): 75°F; Highest Heat Index (through 3 AM Friday): 91°F at 5 PM
St. Cloud Airport 24-Hour Melted Precipitation (through 3 AM Friday): None; SCSU 24-Hour Precipitation (through 3 AM Friday): None

Next Update: Saturday, August 9, 2025 6 AM

Let me know what you think about this forecast and discussion by emailing SCSU meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!

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