textproduct: Twin Cities

KEY MESSAGES

- Long duration period of heat and humidity begins Sunday, persisting through the week. Monday will be the hottest day, but heat impacts to be felt all week with little overnight relief and therefore a building heat stress.

- Conditional chances for thunderstorms exist Sunday through next week. Storms will be capable of severe weather & torrential rain, if they are able to form.

DISCUSSION

Issued at 203 PM CDT Fri Jun 26 2026

Another 36 hours of seasonable weather is expected ahead of the heat and humidity. Radar depicts a few returns across southern Minnesota this afternoon, but nothing is reaching the ground. Highs in the upper 70s today and mid 80s tomorrow will be met with overnight lows in the low 60s and mid 60s respectively. Little chances in the way of precipitation through Saturday evening given the large cap that is forecast to be in place. Storms will develop in the Dakotas later on Saturday and progress into western Minnesota overnight into Sunday morning. Scattered storms are most likely after sunrise on Sunday for most, but the cluster of storms that originated in the Dakotas could clip central Minnesota pre-dawn. For the most part, that earlier activity should stay to the north, with more scattered storms to follow between 5AM-12PM.

Sunday afternoon is when the heat begins to build with an amplifying ridge. Highs will be in the low 80s (west WI, central and east MN) to low 90s (south and southwest MN), but heat indices will be 5 to 10 degrees warmer than that due to an influx of moisture and thus higher dewpoints. Again, strong capping should prevent any thunderstorms from developing over much of our area, but monitoring will be necessary. The current forecast generally keeps Sunday evening storms to the north, with areas along a line from Mora to St.Croix Falls to Eau Claire on the southern edge of where activity would be most likely. Although chances are on the lower end, we continue to remain alert to the threat for severe thunderstorms and heavy rain across central and eastern MN/western WI Sunday night.

With areawide max heat indices at or greater than 105, Monday is certainly the day with attention grabbing numbers. Just how high temperatures/the heat index go will depend on cloud cover and potential precipitation, but we will without a doubt be approaching/at dangerous heat risks. Air temperatures should generally remain in the 90s, with hottest values in western MN potentially over 100. Therefore, record-breaking temperatures are not likely (STC/MSP/EAU all have record highs greater than or equal to 100 for the late June/early July timeframe). What makes this heat dangerous is the warm overnight lows and high dewpoints leading to high heat indices. This level of heat will especially be dangerous for anyone without reliable air conditioning, those working outdoors, young children, older adults, and people with chronic health conditions.

Monday will have the highest temperatures, but the heat impacts will continue, if not worsen, well into the week. Overnight temperatures (lows in the upper 60s and low 70s) and oppressive dewpoints (60-70+) will contribute to a long duration heat risk with little overnight recovery. This will build the heat stress, potentially lasting into the holiday weekend. Heat headlines are inevitable at some point in the near future.

Now to pivot to the thunderstorm and heavy rain threat through the period. The AIFS Ens is forecasting PWATs anywhere from 120-160% for much of the week, leading to an increased threat for torrential rainfall anywhere storms are able to form. As one could imagine with ample heat and moisture, there will be gobs of instability available. The ECMWF is forecasting MUCAPE values greater than 1500 J/Kg Sunday through the 4th, peaking as high as 5000-6000 J/Kg. Take this information with a grain of salt given the large cap that will likely be in place. Another thing to consider relating the storm to heat threat is that if storms do occur at a given location, that will bring at least temporary relief to the heat risk.

To summarize, a conditional severe weather threat is present most (all?) days next week. The key will be to keep a close eye on potential forcing to see what storms may come to fruition. If we tap into instability, things will get interesting storm wise given the highly primed environment. IF storms go, they'll go. It isn't worth the time to try and pinpoint specifics at stage. Once CAMs are available, the threat could be more refined.

AVIATION /06Z TAFS THROUGH 12Z SUNDAY/

Issued at 141 AM CDT Sat Jun 27 2026

VFR through the period with SCT/BKN mid-level clouds. Southeast winds through the period increasing to 10-15 kts by late morning, along with wind gusts of 20-25 kts.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/ SUN...MVFR CIGs/TSRA possible early. Wind SE 20G30 kts. MON...VFR. Chc PM TSRA. Wind S 15-20G30 kts. TUE...VFR. Wind SW 15-20G30 kts.

MPX WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None.