The heat index in the Twin Cities is expected to climb near 100 degrees on Sunday and then topple the 100-degree mark on Monday.
The National Weather Service has issued an excessive heat warning for the Twin Cities metro area and parts of west-central Minnesota beginning Sunday at 1 p.m. and lasting until 1 a.m. Tuesday.
"A building dome of very hot temperatures settles in and continues through early next week before a frontal boundary arrives late Monday/early Tuesday," says the Twin Cities office of the National Weather Service. "Due to the anticipated heat and humidity, an excessive heat warning and heat advisory has been issued for a large area of southern and central Minnesota."
The maximum heat index in Minneapolis-St. Paul is projected to be 107 degrees around 3 p.m. Monday. The hottest stretch is expected to be Monday from about noon until 6 p.m.
The airmass is going to be extremely sticky. Temps Monday will rise into the upper-90s and be coupled with dew points in the low 70s. That's tropical, and also the reason the heat index could get as high as as the NWS is forecasting. The dew points in the 70s will actually keep the air temp from rocketing over 100 degrees, but either way it's going to be very sticky.
The forecast high Tuesday is still around 90 in the Twin Cities, but some of the humidity should be gone, according to the weather service.
There's also a risk of strong or severe storms on Monday, though they are expected to be isolated at best as there is a strong cap in place and storms might have a hard time firing.