Southwest Swelters As Heat Expands Eastward | WeatherBug
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Southwest Swelters As Heat Expands Eastward

June 20, 2021
UPDATED By WeatherBug Meteorologists
The first day of summer and Father's Day will begin with triple-digits grilling much of the western and central U.S. 

The early and intense June heat wave is caused by a large dome of high pressure and an upper-level ridge expanding from the Interior West into the central Plains. This is producing abundant sunshine throughout the West, causing daily afternoon temperatures to skyrocket into the triple digits. The only relief from the heat will be an afternoon or evening storm, but those look to be few and far between.

Excessive Heat Warnings and Heat Advisories drape the western U.S., extending from much of California, Nevada and Arizona. Stockton, Death Valley, Calif., Las Vegas and Reno, Nev., Phoenix and Tucson, Ariz., are just a few cities included in the long list. These have recently expanded into parts of New Mexico and western Texas and hot temperatures in the upper 90s and triple digits reach as far east as St. Louis.

The extreme heat is also increasing the risk of wildfires. Red Flag Warnings are in place for Utah and western Colorado into southern Idaho. The combination of such warm temperatures, gusty winds and low relative humidity values will create critical, fast-spreading fire weather conditions.

Not only will this heat challenge or smother record highs for many, but little in the way of relief is coming at nighttime in urban locations, with lows failing to fall much below 80 degrees. These warm lows will also serve as a launching point to boost afternoon highs well into the 90s and triple-digits, or 10 to nearly 30 degrees above normal for mid-June.

The hottest temperatures will be found in the Desert Southwest and southern Great Basin as temperatures soar to as high as 120 degrees while California’s Central Valley and the Sierra Nevada foothills see temperatures soar to near 110 degrees. Toasty, widespread upper 90s to lower and middle 100s will also blanket northern Utah. Hot 90s and triple-digits will also bubble central Plains and Middle Mississippi Valley before much cooler temperatures arrive for the start of the workweek.

The records continue to fall in the heat. Bakersfield, Calif., hit 110 degrees Saturday, besting the old record of 109 degrees set in 2017. Fresno, Calif., had a high temperature of 111 degrees, shattering the 108-degree record also set in 2017.

This heat wave is dangerous and deadly and should be treated as such. It cannot be said enough: if you cannot avoid being outdoors, especially during peak heating from late morning to early evening, make sure to drink plenty of fluids to stay well-hydrated. Wear lightweight and loose-fitting clothing and make sure to check on those most vulnerable: the elderly, children, and pets.