The National Weather Service has 62 heat advisories active Monday across 16 states, nearly double the 33 alerts posted a day earlier, as the heat dome driving the multi-day event pushes into new territory including New Jersey, Ohio and Florida.
The advisory footprint now stretches from Montana’s high plains through the Upper Midwest, the Northeast and into Puerto Rico, covering California, Florida, Massachusetts, Maine, Michigan, Minnesota, Montana, New Jersey, New York, Ohio, Pennsylvania, Puerto Rico, South Dakota, Vermont, Wisconsin and Wyoming. Colorado, Idaho and Nevada, all under advisories Sunday, have dropped off the list, while Florida, New Jersey and Ohio are newly affected.
Wisconsin carries the heaviest concentration of alerts, with heat index values forecast up to 102 in east central, south central and southeast counties through 8 p.m. CDT Wednesday, and up to 105 in the northeast part of the state through 9 p.m. this evening. The advisory zone there spans dozens of counties from Marquette and Sheboygan south to Racine and Kenosha, and west to Vilas and Oneida.
The Northeast has become a new focal point overnight. The National Weather Service has posted advisories across a broad swath of New Jersey and New York, including all five New York City boroughs, Long Island’s Nassau and Suffolk counties, and the Hudson Valley, alongside Connecticut and southern New Hampshire counties. In Maine, heat index values of 95 to 99 are expected through 8 p.m. EDT in Piscataquis, Penobscot and surrounding counties.
Out west, South Dakota has the largest single-state alert count, with advisories covering the Black Hills region, the Pine Ridge and Rosebud areas, and the state’s northern and eastern plains counties, from Harding and Butte in the northwest to Todd and Tripp in the south central part of the state.
The National Weather Service is urging residents across the advisory zone to drink plenty of fluids, stay in air-conditioned spaces, avoid direct sun exposure and check on relatives and neighbors, particularly those without air conditioning. Officials also warned that children and pets should never be left unattended in vehicles. In outdoor and agricultural work settings, forecasters pointed to Occupational Safety and Health Administration guidance for reducing heat-related illness risk.
With the alert count nearly doubling in 24 hours and new states added in both the Northeast and Southeast, forecasters say the heat is likely to persist into midweek before any significant relief arrives, particularly across Wisconsin, where some advisories extend through Wednesday evening.