Nearly 87 million people from coast to coast are feeling scorching temperatures as much of the southern tier of the country is dominated by a giant ridge of high pressure that shows no signs of breaking down.
"All of this happening as a result of a strong ridge of high pressure," FOX Weather meteorologist Jason Frazer said. "What is basically doing in the upper atmosphere? It's doing a little dosey doe … a little square dance. It's not really going anywhere. And as a result, we're not able to get that jet stream to move a little bit more downward to allow some of that relief."
Highs in the Southwest and the southern High Plains will easily reach the triple digits, with upper 90s and lower 100s expanding into more of the central and southern Plains.
Las Vegas could challenge its all-time record high of 117 degrees by Sunday with a forecast temperature of 117. It last tied the record on June 20, 2017.
In Death Valley, California, afternoon highs could approach 130 degrees this weekend, with overnight lows not even slipping below 100.
In Texas, Excessive Heat Warnings and Heat Advisories are in effect to account for heat indices up to 110 degrees.
Hazardous heat is expected to expand across the southern tier through at least this weekend – and likely beyond – as the upper-level ridge of high pressure strengthens over the South and stretches into parts of the West.
On Saturday, there's no doubt that it's going to be hot in Arizona. But it'll be scorching in cars in Arizona to the point where you could possibly bake cookies if you leave them in a car undisturbed for a couple of hours.
Already, Phoenix had 12 consecutive days with temperatures of 110 degrees or higher through Tuesday, and the forecast for the next week keeps highs near or above 110. Phoenix's all-time record for consecutive days at or above 110 degrees is 18 days, set in 1974.
It's not just during the day that places like Phoenix must deal with the heat.
Far-above-average temperatures will expand from the southern High Plains into the Southwest and California, with the potential for numerous daily record highs and record-warm overnight lows possible.
Farther east, air temperatures should be closer to average for mid-July, but the real story will be high humidity leading to heat indices between 105 and 115 degrees for a large portion of the South from eastern Texas into the Southeast.
Temperatures into the 90s to near 100 degrees are possible by Thursday farther north into the central Plains, but it should cool off in that region by the weekend.
The start of the 2023 monsoon season will continue to be on hold as long as this pattern stays locked into place, the FOX Forecast Center said.
The combination of the lack of rain over much of the West and the sweltering heat could lead to many long-term problems.
South Florida sizzles in rare extreme heat event
Another hot and humid day is forecast Wednesday for South Florida, with forecast highs in the mid-90s and widespread heat indices between 105 and 110 degrees.
Due to the increased risk of heat-related illnesses, a Heat Advisory remains in effect through at least Thursday.
With lower-than-usual thunderstorm coverage expected, excessive heat will likely continue through the majority of this week as afternoon high temperatures reach the lower to mid-90s across most locations in South Florida.
A heat index of 110 degrees in Miami is very rare, and the chance of it occurring on any given day is less than 5%. Miami International Airport recorded a heat index of 110 for two straight days on Sunday and Monday. However, Tuesday's peak heat index "only" reached 108 degrees.