CHICAGO — Dangerous heat spread across broad areas of the eastern and central United States on Friday, prompting weather officials to issue warnings and advisories as prolonged high temperatures and humidity increased the risk of heat-related illness across multiple states.
The U.S. National Weather Service warned that a strong upper-level ridge was sustaining unusually hot conditions from the Northern Plains and Upper Midwest into the Ohio Valley, with the heat extending farther east toward the Mid-Atlantic. Forecasters said daytime temperatures in many locations were expected to reach the upper 90s to above 100 degrees Fahrenheit (35–38 degrees Celsius), while high humidity would push heat index values significantly higher.
The Weather Prediction Center said dangerous heat would continue across parts of the north-central United States through the end of the week before gradually shifting southward over the weekend as a cold front moved into the Northeast. Areas of the Ohio Valley and Mid-Atlantic were expected to experience some of the hottest conditions on Friday before modest relief reached northern locations early next week.
The National Weather Service urged residents to limit strenuous outdoor activity during the hottest part of the day, remain hydrated, seek air-conditioned environments when possible, and check on older adults, children and others at greater risk from extreme heat. Officials also warned that warm overnight temperatures would reduce opportunities for recovery from daytime heat, increasing health risks during the extended event.
Forecast products highlighted a high risk of extreme heat across portions of the Northern Plains on Friday and moderate risks extending across the Central Plains, Upper Mississippi Valley, Ohio Valley, Tennessee Valley and parts of the Southeast through Saturday. A broader slight risk covered much of the country from the Great Plains to the East Coast through early next week.
The hot pattern developed under a persistent area of high atmospheric pressure, commonly referred to as a heat dome, which suppresses cloud formation and allows temperatures to build over successive days. Meteorologists said the same weather pattern also supported dry conditions in some regions while monsoonal moisture increased the likelihood of thunderstorms across parts of the Southwest and Rockies.
The latest forecasts indicated that heat advisories and warnings would remain in effect across many eastern and central states as officials continued monitoring conditions and urged the public to follow local weather guidance.
