Excessive heat is ramping up in the West into the weekend
After soaring to a record high of 118 degrees in Phoenix on Wednesday, temperatures Thursday morning dipped only a handful of degrees below the century mark. The preliminary low of 95 degrees is among the hottest on record for the city. And it comes as an excessive-heat warning continues through Thursday evening from about Palm Springs, California, to Phoenix, then south to the Mexican border.
Heading into the weekend, temperatures to climb higher to the northwest.
Heat advisories go into effect Friday and last through at least Sunday for Northern California. Excessive heat watches are also in place for portions of that region into southern Oregon beginning Saturday afternoon, with the expectation of temperatures around and above 100 degrees widespread early next week.
The high of 118 degrees in Phoenix on Wednesday was America’s hottest city’s hottest temperature of the year so far. It also stands as a tie for the sixth hottest maximum value on any day and in any year there; it had last reached 118 in 2024.
Wednesday’s high beat a daily record of 116 degrees that was also set last year. The all-time maximum temperature for Phoenix is 122 degrees, on June 26, 1990.
It remained extremely hot through Wednesday night and into early Thursday in Phoenix. Temperatures were at or above 102 degrees through 2 a.m.
After dipping to 99 degrees at 3 a.m., the mercury rose to 100 again at 4 a.m., which tied for the hottest mark at that time of morning on record, according to data from the Iowa Environmental Mesonet.
The preliminary morning low temperature of 95 degrees is a record for the date, besting 92 degrees in 2024. It’s also among the hottest morning lows observed, should it hold through the day. Given the forecast of no storms, it probably will.
Increases in overnight lows are a particularly notable aspect of human-caused climate change. As recently as the mid-1990s, Phoenix averaged about one day annually with a low at or above 90. Today, that average is up to 10 days, and there were a record 39 such mornings in 2024.
- – -
Other hot spots
Phoenix isn’t alone in the too-hot-to-go-outside category. Other locations reaching seasonal highs Wednesday included Thermal, California (120 degrees), Palm Springs (119 degrees) and Las Vegas (110 degrees).
The nation’s hot spot, Death Valley, reached 123 degrees Wednesday, which is the hottest day of the year there so far. The prior top reading of the year for the United States was 122 degrees, also in Death Valley, on June 15.
- – -
Somewhat less intense Thursday
It shouldn’t be as hot Thursday in Phoenix or in other nearby areas. Instead, highs of about 110 to 115 degrees will be common – still about 5 to 10 degrees above average for the date.
An excessive-heat warning continues through this evening. Tonight’s forecast offers a comparatively comfortable low near 90.
Temperatures may nudge slightly downward in the days to come for the hottest locations of the Arizona desert, but highs around 110 are expected for the near future in Phoenix as storm chances remain hard to come by and the region remains in extreme drought.
- – -
What’s next?
A heat dome center in place near the Southern California coast into the Desert Southwest stays more or less stationary into early next week, while intensifying for a time into the Pacific Northwest.
Record highs should become common from Northern California into Oregon by Sunday. Temperatures of 100 degrees to as high as 110 degrees are anticipated, which is about 15 to 20 degrees above average.
Under a heat watch starting Saturday, Medford in southern Oregon is forecast to spend at least a handful of days near or above 105 degrees. Records are possible, particularly by Tuesday, when the forecast is 107 degrees.
Temperatures appear to stay above normal in the Western states beyond early next week. A wildfire threat may also increase over time, although light winds are favored amid the hot afternoon readings.