The National Weather Service’s active heat alert count eased slightly to 83 Saturday, down from 89 a day earlier, but the footprint kept expanding — advisories and warnings now cover 25 states and Puerto Rico, up from 21 states Friday, as hot air pushes into the Southeast and Gulf Coast.
Alabama, Louisiana, Mississippi, Tennessee and Puerto Rico joined the alert list in the past 24 hours, while Florida dropped off. The heat has now touched territory from the Pacific Coast to the Southeast, with the heaviest concentration still centered on the Plains and Upper Midwest.
The most severe conditions remain in Nebraska and Iowa, where the National Weather Service has posted an Extreme Heat Warning for heat index values up to 112 degrees. A broader Heat Advisory across the same region covers heat index readings up to 108. Forecasters there also flagged overnight lows in the mid to upper 70s, meaning little relief for residents before the heat rebuilds the following day.
In Wisconsin, where advisories stretch from Marquette and Green Lake counties south through Milwaukee, Racine and Kenosha, heat index values of 100 to 103 degrees are expected through 9 p.m. CDT Saturday. The National Weather Service noted that areas along the immediate Lake Michigan shoreline may see limited relief from an afternoon lake breeze, while inland communities see none.
The alerts span a wide swath of counties in Iowa, Nebraska, Minnesota and Wyoming, along with the Wisconsin counties named above — illustrating how the heat dome is affecting rural and urban areas alike rather than concentrating in major metros. In Wyoming, advisories cover the Bighorn Basin, Wind River Basin and Natrona County’s lower elevations.
The National Weather Service’s standard guidance remains in force across the alert zone: drink plenty of fluids, stay in air-conditioned spaces, avoid prolonged sun exposure, wear lightweight and loose-fitting clothing, and check on relatives and neighbors, particularly those without reliable air conditioning.
What’s changed since Friday is less about intensity and more about reach. The slight dip in total alerts — 89 to 83 — suggests some advisories in the original Plains and Southwest core have expired or been consolidated even as the system spreads into new territory. With alerts now active as far south as the Gulf Coast and into Puerto Rico, the heat dome shows no sign of contracting; forecasters will be watching whether the Southeast expansion holds through the workweek or whether the core intensifies again over the Plains.