Parts of Minnesota will see heat index top 105 by Wednesday

Temperatures and humidity dive the second half of the week

A boy enters a wading pool.
Jereny G. Jr. enters at the Wabun Picnic Area wading pool during a heat wave in Minneapolis in June.
Tim Evans for MPR News file

Heat, humidity and strong storms continue to provide challenges for Minnesota through Wednesday, then the weather pattern shifts back to more typical July warmth.

Tuesday’s forecast

The storms that brought severe weather to portions of northern Minnesota have cleared into Wisconsin as of Tuesday morning. 

There is a chance a few more storms could develop in southern Minnesota Tuesday, especially in the evening or overnight. If that occurs, those storms may bring large hail and damaging winds.

However, it is likely that most of Minnesota stays sunny through the day Tuesday. 

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Although there were a few 50s and 60s north where humidity levels are slightly lower, most of southern Minnesota started Tuesday off muggy and warm in the 70s. 

The entire state stays above average for highs, with all but the northeastern corner of the state making it into the 90s.

weather graphic
Tuesday high temperatures
National Weather Service

In southern Minnesota, where the dew points are expected to surge into the 70s by the afternoon, the heat index will push past 100 in some spots. 

weather graphic
Forecast heat index temperatures Tuesday
National Weather Service

Because of the dangerous heat, most of southern Minnesota is under a heat advisory Tuesday.

weather graphic
Heat advisory Tuesday;, excessive heat watch Wednesday
National Weather Service

Even hotter Wednesday

Temperatures turn even hotter Wednesday, with the southern half of the state mostly in the mid and upper 90s, and southwestern Minnesota likely to see a few 100s.

Dew points also stay tropical in the south, in the upper 60s and low 70s. That mix of hot humid weather will put the heat index above 100 for most of southern Minnesota, and many locations, especially near the Mississippi River Valley could feel like over 105 degrees.

weather graphic
Forecast heat index temperatures Wednesday
National Weather Service

Because of the dangerous heat, most of southern Minnesota is under an excessive heat watch Wednesday, and there is a good chance that will be upgraded to an excessive heat warning.

Showers and storms are also more likely to return Wednesday, with some scattered activity possible at any point during the day. Especially in eastern Minnesota, some of those storms could become severe, with hail the primary threat. Damaging winds and isolated tornadoes are also possible.

weather graphic
Severe weather outlook Wednesday
National Weather Service

That risk increases to more numerous strong storms forecast as you head into Wisconsin. Outside of heavier rain with thunderstorms, rain totals remain low.

Extended forecast

Fortunately, a cold front finally passes through Minnesota from north to south on Wednesday, with the timing currently looking like Wednesday afternoon through late evening.

That is expected to drop temperatures for most of Minnesota by about 10 degrees by Thursday and lower the humidity. 

weather graphic
Twin Cities temperatures trend through Saturday

Here is the forecast for the Twin Cities showing that temperature drop (Wednesday’s high may be a couple of degrees warmer than this model shows):

Those more seasonable temperatures should last through at least the first half of next week. Unfortunately, the state is also forecast to go back into a drier pattern as well.

Programming note

You can hear my live weather updates on Minnesota Public Radio at 7:48 a.m. Monday through Friday morning.