Record heat to hit Las Vegas, California’s Central Valley this weekend
A short-lived but punishing blast of intense heat will spread over the western United States through Saturday, pushing temperatures 10 to 20 degrees above normal for this time of year across California, Nevada and as far north as Montana.
An extreme heat warning is in place for Las Vegas and nearby locations. The city is expecting temperatures near 100 Thursday, rising to around 105 Friday and Saturday.
A heat advisory is in effect for much of central and Northern California, including portions of the Bay Area — but not San Francisco itself. Highs near 100 should approach places including Napa, while the Central Valley will run to 105 degrees or higher.
The federal government’s HeatRisk threat will rise to major (Level 3 out of 4) for a big chunk of the region. Moderate risk (Level 2 out of 4) will also cover a broader area, including much of the Great Basin and north to the Canadian border.
Although the heat wave will be quick, temperatures rising to near-record values, combined with the fact that it’s the first significant heat for many in the region, will lead to additional stresses than might be the case midsummer.
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Summer preview
High pressure dominating Canada, leading to high heat and an early explosion of wildfires, will migrate southwestward in the coming days, partly in response to a big dip in the jet stream developing over the northeastern United States. With the most unusual strength of high pressure centered near the northern Rockies, it will drag 100-degree heat well north.
For the first time this year, the century mark is in reach for places like the Snake River Valley of Idaho on Saturday. On the same day, much of the Central Valley in California should rise to around 105 degrees.
Some of the stifling highs forecast for Friday and Saturday include:
• Redding, California: 106 Friday / 103 Saturday
• Las Vegas: 104 / 105
• Palm Springs, California: 104 / 103
• Phoenix: 104 / 101
• Sacramento: 102 / 100
• Boise, Idaho: 90 degrees / 101 degrees
Even coastal locations of central and Southern California should see readings rise into the 70s or 80s, with light offshore winds keeping thicker fog at bay. A little farther inland around Los Angeles, highs are expected to reach the upper 80s.
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Records should be numerous
Dozens of record highs are probable, with the greatest concentration from central California and Nevada northward to the northern Rockies. Numerous records for warm lows are also primed to be broken, from Ramona, California, near the border with Mexico, to Havre, Montana, near the border with Canada.
Existing records of 106 on Friday and 104 on Saturday are both under threat in Las Vegas.
Saturday’s record may be more likely of the two to fall. It was most recently set on the same date just last year, before the city went on to witness its hottest day — 120 degrees on July 7 — and the highest number of 100-degree days on record, with 112.
Death Valley, considered the hottest place on Earth, should reach the upper 110s. If it reaches the forecast of 119 Saturday, it would be a record for the date, and the hottest the country has seen so far during this warm season. The current holders of that prize are Rio Grande City in Texas and Death Valley, which both had 112-degree readings in mid-May.
Should the mercury rise that high, it would be one of the earliest in a year.
Although it will be a short burst of extreme heat, the unusual intensity of high pressure is a marker of human-caused climate change. In addition to more frequent heat, stronger surges of heat are hallmarks.
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Early-season risks
With the heat wave coming on the first weekend of unofficial summer following Memorial Day, the National Weather Service also warns of threats on the water.
“Area waterways continue to run cold and fast, creating dangerous conditions for those seeking relief in rivers and lakes,” the Weather Service office in Sacramento noted.
With increased snowmelt, given the hot conditions, the potential for hypothermia and being swept downriver are primary concerns.
Hot weather is also generally more stressful early in the season than later, as people are not yet acclimated to it. Staying hydrated, wearing light-colored clothing and avoiding strenuous outdoor activity during the day are keys to staying healthy in the heat.
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Relief won’t wait long
This blowtorch will be short-lived.
We can thank several low-pressure areas on the map next week. One will pass through Canada, while a mixture of an upper-level low and remnants of a tropical storm in the eastern Pacific Ocean will focus on southern reaches. The latter could bring increased moisture, some rain and cooler air to the Desert Southwest by Sunday night.