The National Weather Service issued the warning at 2:43 AM CDT Sunday for Hennepin County and six other metro counties, and it's not messing around: heat index values up to 101 during the day, and lows only falling to around 75 at night. That last part is the sneaky danger — no real overnight cool-down means bodies don't get a chance to recover before the next hot day starts.
The numbers: sunny and 94 today with heat index near 99, a low of 73 tonight, then 96 Monday and 96 again Tuesday before the warning lifts at 9 PM. Winds stay light out of the southwest the whole stretch, 5 to 10 mph, so there's no real relief coming from that direction either.
For anyone with plans at the parks, on the trails, or just running errands outside — this is three days in a row of dangerous heat, not a one-afternoon spike. NWS points to a significant jump in heat-related illness risk during stretches like this. If you've got outdoor plans through Tuesday, morning is your window; midday and afternoon are when the heat index numbers climb toward that 99-101 range.
Nights offer only modest relief — 73 tonight, 74 Monday night — so if your house or apartment doesn't cool down well, that's the stretch to have a backup plan for staying cool. The warning runs through 9 PM Tuesday, when temperatures are expected to ease back down after that.