A heat dome and "corn sweat" are driving this week's dangerous heat wave
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A heat dome — plus the "corn sweat" phenomenon in some areas — is bringing dangerous levels of heat and humidity to much of the country east of the Rockies this week.
Why it matters: Heat warnings and advisories stretch from Louisiana and the Florida panhandle up to Chicago and beyond as of Tuesday afternoon, covering nearly 85 million Americans.
Driving the news: The main driver is hot, moist air being drawn up from the Atlantic and trapped by a high pressure ridge.
- Also contributing in some places: "Corn sweat," wherein vast amounts of growing corn and other produce give off moisture through evapotranspiration, further increasing humidity levels in and around agricultural zones.
- "While corn sweat is never the main reason for major heat," Axios Des Moines' Linh Ta wrote back in 2023, "it can add to it."
What they're saying: "This is the time of the year when humidity contributions from corn sweat are highest — around the time of tasseling and pollination, when the flower emerges from the corn stalk," as Iowa state climatologist Justin Glisan told the Washington Post.
Zoom in: Conditions could be particularly brutal in Chicago, where the local National Weather Service office is warning of heat indices over 105°F for Wednesday and Thursday.
- High humidity is especially dangerous, as Axios' Tina Reed and Natalie Daher recently reported, disrupting our bodies' ability to regulate temperatures.
Threat level: Long-duration heat waves can be particularly serious events, with warm evenings offering less of a reprieve and extreme heat having a cumulative effect on our health.
- Extreme heat is the most deadly weather event in the U.S., and research has shown that human-driven climate change is making such events both more intense and more frequent.
"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors," the NWS Milwaukee office advises.
- "Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes."
What's next: The risk of extreme heat continues through next week for parts of the Central and Southeastern U.S., per the NWS Climate Prediction Center.
Go deeper: Millions of U.S. kids attend schools in "urban heat zones"
