Record-breaking southwestern US heat wave to expand eastward this week
The Southwestern states have been roasting amid the most intense heat wave of the summer so far this year, and AccuWeather meteorologists say Mother Nature will provide no cooling relief in the near term. In fact, the heat is expected to expand its reach into the latter part of July.
Tens of millions of Americans remained under heat-related weather alerts at the start of the week from the Desert Southwest into the southern Plains, and even as far east as Alabama and Florida. Within that large region, excessive heat warnings were in effect from Southern California to Mississippi as of early Wednesday morning.
Phoenix recorded its third consecutive record high temperature on Saturday as the thermometer soared to 118 degrees Fahrenheit, beating out the previous record for the date of 117 set in 1998. Although the city dubbed "The Valley of the Sun" is accustomed to extreme conditions during the summertime, temperatures so far this month have been particularly stifling. Similar temperatures have followed as well, with the mercury reaching 114 and 116 on Sunday and Monday, respectively. Another record high was set on Tuesday, as the high temperature soared to 118 degrees again, shattering the record of 115 degrees set in 1989.
The city is on track to climb above 110 F each day through at least the end of the weekend. Thursday's expected high of 117 would break a record last set in 1978.
For nine days in a row, low temperatures have not dipped below 90 in Phoenix. This broke the old record of seven days in a row in July and August 2020 and in August 2012. Currently, Phoenix is forecast to stay above 90 around the clock into the end of this week.
"These temperatures are occurring during the time of year when temperatures are already typically at their highest relative to historical averages," AccuWeather Meteorologist Joe Bauer said.
Through the first half of July, temperatures were roughly 3-6 degrees above the historical averages across the Southwest.
"With a large area of high pressure locked in place overhead, the weather pattern will continue to promote extreme heat across the Southwest," AccuWeather Meteorologist Andrew Johnson-Levine said.
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Temperatures may have peaked during the heat wave this past weekend but may only slip back by a few degrees this week. Temperatures will remain at record-challenging levels, 5-10 degrees above the historical average, into next weekend.
In one of the hottest locations on Earth, lying nearly 300 feet below sea level, Death Valley, California, reached 124 F on Monday. Similar high temperatures are forecast to persist through much of this week.
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Salt Lake City reached 106 degrees on Sunday, which was only 1 degree shy of the all-time high of 107 set on multiple occasions.
"The extreme heat and blazing sunshine can cause most individuals to become rapidly dehydrated. People are urged to avoid strenuous activity during the daylight hours, to increase their intake of fluids and seek an air-conditioned environment when possible to avoid the potential of heat exhaustion and heatstroke," AccuWeather Senior Meteorologist Alex Sosnowski said. "Even though many all-time record highs may remain intact during the heat wave, this is still about as hot as it ever gets over the interior Southwest, so it is dangerous and serious."
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"In addition to the daytime highs, temperatures will remain well above the historical average at night. In cities such as Las Vegas and Phoenix, record high minimum temperature records could be threatened," Johnson-Levine said.
The long-duration heat wave, accompanied by mostly dry weather, can act to elevate wildfire concerns in the coming days and weeks as vegetation continues to dry out.
"Precipitation from this past winter led to an increase in the growth of sagebrush and grasses in the region. This vegetation then becomes fuel for wildfires to develop during much of the balance of the summer and into the fall," Sosnowski said.
People in El Paso, Texas, have endured 33 days in a row with high temperatures at or above 100 F as of July 18. The string of days began a month earlier on June 16 with the highest temperature of 110 on June 26. Many more days of triple-digit heat are in store for the Sun City, which will add to the old record that was shattered from July 1994 with 23 consecutive days of highs at or above 100.
As the high pressure system over the Southwest broadens its reach this week, AccuWeather meteorologists say temperatures will rise to record-challenging heights farther to the east as well.
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Temperatures in El Paso are projected to hit record-breaking levels through the middle of the week, perhaps flirting with or exceeding 110 on multiple occasions.
Dallas is forecast to reach the 100s through at least Thursday, following a brief return to more seasonable temperatures at the end of the weekend.
High heat is set to expand even farther east through the middle to end of this week. Montgomery, Alabama, is set to reach the upper 90s each day through Friday, while Jackson, Mississippi, could make a run at the century mark on those days. Even as far east as Savannah, Georgia, a high near 100 F is forecast for Wednesday and Thursday. When combined with very high humidity, AccuWeather RealFeel® Temperatures in the Southeast will be comparable to those seen in Texas and the Southwest states.
"The annual event that sparks thunderstorms over the Southwest, known as the North American monsoon, will continue to be suppressed over the next week or two at least. This change in wind direction that allows moisture to creep northward from the tropical Pacific, Mexico and the Gulf of Mexico has been delayed," Sosnowski said.
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AccuWeather forecasters cannot rule out a cooling thunderstorm or two to develop over the high terrain of the Four Corners region in the coming week, but many of the storms may bring little or no rain and could kick up dust or trigger lightning-induced wildfires.
Early indications point toward the hot, dry weather only growing more intense across the West toward the last week of July, perhaps expanding northward as well into the Northwestern states as the jet stream bulges into western Canada.
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