Heat Wave Stretches Across South, Western U.S.

Sweltering temperatures across the U.S. southern tier expand today as both humid and torrid heat deepen.

A heat dome remains parked above the western half of the nation this week, creating a toasty environment from Mexico to Canada. The crux of the heat today, however, will be found within the Great Basin and Desert Southwest.

Afternoon high temperatures peaking at 100 to 115 degrees are expected across the Desert Southwest, with isolated basins in the Sonoran Desert blazing into 120 degrees, such as in Death Valley, Calif. Further north and east, in the Intermountain West's valleys and amongst the High Plains, valley and lowland temperatures will hit between 90 and 100 degrees.

Mainly south and east of the Oklahoma Panhandle, high moisture surging from southern gulfs and seas will instead create a damp heat, sweltering across the South and even the coastal plains of the Mid-Atlantic and southern New England. The heaviest heat will hit the southern plains, with the heat index largely sweltering above the century mark and even grazing 110 degrees in spots. East of the Mississippi River, the South and East Coast will top out in the mid-to-upper 90s.

As if that were not enough sweating, overnight lows in the south-central Plains will stall in the 80s, with the Desert Southwest bottoming out in the 80s, and even 90s in localized basins. Warm low temperatures such as these, in combination with the high humidity in place, can lead to an increased risk of heat-related illness, and could have an impact on power, water, and transportation systems.

Extreme Heat Warnings and Heat Advisories are prevalent today. Areas under these postings include the Pacific Northwest, the San Joaquin Valley, the Sonoran Desert, the Mojave Desert, the Great Basin, portions of the south-central Plains, and eastern Pennsylvania to southeastern New Hampshire.

If you are in one of these areas experiencing extremely hot temperatures, it is exceptionally important to stay hydrated and cool. Avoid exposure to the sun from late morning into the early evening. Make sure to take frequent breaks in the air conditioning or shade, eat and dress lightly, and to use sun protection if outdoors. Always check the back seat before exiting your car, as a vehicle can reach 30 to 40 degrees higher than outdoor temperatures. Never leave kids or pets unattended and remember to “Look Before You Lock!”