The National Weather Service has issued a heat advisory for much of Indiana beginning Monday through 8 p.m. Thursday, with heat index values expected to reach 105 to 108 degrees.
Forecasters say the combination of high temperatures and oppressive humidity will make it feel much hotter than the actual air temperature, increasing the risk of heat-related illnesses for anyone spending time outdoors.
“We’re forecasting highs in the lower 90s for now, but one big factor is the humidity,” said Matt Eckhoff, a meteorologist with the National Weather Service. “We had a lot of rain recently, especially down south, and that moisture is going to add to the humidity already in the air. For that reason, we’ve issued heat advisories and heat warnings through Thursday,” he said.
The upcoming heat wave follows nearly two weeks of repeated rounds of rain and severe storms. Eckhoff said the change in weather is being driven by a shift in the jet stream.
“The jet stream has been basically directly overhead, and that’s a highway for storm systems,” he said. “It has been one after another. That jet stream finally looks like it’s going to lift northward back into Canada. When that happens, the warm air rapidly flows northward, and we’re going to be in a hot and humid air mass basically blasting through the whole week.”
The humidity also makes the heat more dangerous because it limits the body’s ability to cool itself.
“When it’s humid, your sweat doesn’t evaporate,” Eckhoff said. “Your body can’t cool itself or regulate its temperature, so your internal core temperature rises much quicker when you’re also dealing with extreme heat.”
Another concern is the lack of overnight relief. Overnight lows are expected to remain in the low to mid-70s, preventing homes and buildings without air conditioning from cooling down.
“It’ll just get very hot,” Eckhoff said.
He encourages Hoosiers to stay hydrated, limit strenuous outdoor activity during the hottest part of the day, and take advantage of cooling centers if they are available.
“The best thing to do is just be aware of the heat that’s coming, find ways to cool down, and drink plenty of water,” Eckhoff said. “Some counties are starting to open cooling centers. If you don’t have air conditioning, take advantage of them.”
