The National Weather Service has posted 56 active heat alerts stretching across 23 states, from northern New England to the Gulf Coast and west into the Plains, as forecasters warn of heat index values reaching up to 105 degrees in some areas through the week.
The advisories cover Alabama, Arkansas, the District of Columbia, Georgia, Iowa, Kansas, Louisiana, Massachusetts, Maine, Michigan, Missouri, Mississippi, Nebraska, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, Vermont, Wisconsin and West Virginia. The geographic spread illustrates how widely a single heat pattern can stretch, touching both the humid Southeast and the interior Midwest and Plains in the same alert cycle.
In Maine, the Weather Service has flagged Coastal Washington, Northern Washington, Central Washington and Central Penobscot counties for heat index values up to 104 degrees, with the advisory running from 11 a.m. Thursday to 8 p.m. EDT Friday. Nearby, an Extreme Heat Watch has been layered onto a Heat Advisory for Southern Piscataquis, Interior Hancock and Southern Penobscot counties, where forecasters say heat index values could hit 100 during the advisory period and climb to 105 once the watch takes effect Thursday morning. Northern Penobscot and Southeast Aroostook counties are under a separate advisory for index values near 99, in effect from 11 a.m. to 8 p.m. EDT Thursday.
The heat is not confined to the Northeast. Alerts also cover a band of counties across northern Alabama and the Tennessee Valley, including Madison, Morgan, Marshall, Jackson, DeKalb, Cullman, Lauderdale, Colbert, Franklin, Lawrence and Limestone, along with Greene, Stone and George counties to the south. New Hampshire’s Northern Coos, Southern Coos and Northern Grafton counties are under advisories as well, showing the heat pushing into higher-elevation areas typically insulated from extreme summer readings.
The National Weather Service is urging residents across the affected areas to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check on relatives and neighbors, particularly those without reliable air conditioning. Heat remains the leading weather-related killer in the U.S. in most years, and officials note that heat illness risk climbs sharply when high humidity prevents the body from cooling efficiently through sweat, even when actual air temperatures fall short of record levels.
With advisories active in New England, the Mid-Atlantic, the Ohio Valley, the Gulf South and parts of the Plains simultaneously, residents in cities such as Portland weather and Birmingham weather should expect the heat and humidity to persist through the advisory windows before any relief arrives behind the next frontal passage.