Blistering heat wave in West sets records, escalates fire danger

WEATHER NEWS: Blistering heat wave in West sets records, escalates fire danger


Nearly 50 million Americans are under alerts through Labor Day weekend because of a prolonged heat wave that has already set dozens of records throughout the West.

The “dangerous” heat wave, which began Tuesday, is taxing power grids, fueling fast-moving fires and posing a threat to homeless, elderly and other vulnerable people. Not expected to relent until the middle of next week, it’s an episode notable for its intensity, duration and coverage.

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Since Tuesday, high temperatures over 100 degrees have scorched areas from Southern California to Montana, including record highs of 111 degrees in Fresno, Calif., on Friday, 102 in Salt Lake City on Thursday, 112 in Burbank, Calif., on Wednesday, and 100 in Portland, Ore., on Tuesday. Death Valley, Calif., soared to 124 both Thursday and Friday.

The heat even surged into Canada on Friday, where the village of Lytton set a September record for British Columbia of 103.3 degrees (39.6 Celsius).

Dozens more records are expected to fall through the middle of next week. California’s populous Central Valley is expected to see record-challenging highs between 98 and 113 degrees for the next five days.

The state’s grid operator, California ISO, is calling for customers to voluntarily conserve electricity between 4 and 9 p.m. Saturday — the fourth day in a row to feature a Flex Alert. California ISO is also asking residents to “precool” their homes by setting the thermostat to 72 degrees in the morning, and then raising it to 78 degrees after 4 p.m.

“The power grid operator is again expecting high electricity demand, primarily from air conditioning use, and needs voluntary conservation steps to help balance supply and demand,” the agency wrote.

Gov. Gavin Newsom (D) has declared a state of emergency to free up state resources to address the extreme heat. The proclamation notes that, by Monday, energy demand could exceed 48,000 megawatts, the greatest load of the year.

Highs will run 10 to 20 degrees above average for the western third of the nation, courtesy of a stagnant heat dome, or ridge of high pressure, parked over the Great Basin of Nevada. It won’t budge until Tuesday and will bring hot, dry air that will sink and parch the landscape. The high will also act as a force field, deflecting any storm systems north toward Canada.

The heat will be more reminiscent of July than September across the Golden State, the Desert Southwest, and parts of the northern Rockies.

Scores of heat records have been set since Tuesday, and many more are in jeopardy over the coming days. Here’s a look at some of the new records — most are daily record highs (for calendar dates) but a few, where noted, are more significant monthly records:

  • Redmond, Ore., on Friday set a record high for September, hitting 106 degrees.
  • Fresno, Calif., set a (daily) record high of 111 on Friday.
  • Hanford, Calif., hit a record high of 109 degrees on Friday. On Thursday, it hit 105, tying a record set in 2017.
  • Death Valley, Calif., set a record high of 124 Friday. It also hit a record of 124 on Thursday and 123 on Wednesday.
  • Reno, Nev., hit record highs of 102 on Friday, and 100 on Wednesday and Thursday. The 102 degrees on Friday tied the September monthly record high.
  • Boise, Idaho, tied a record high of 101 Friday.
  • Missoula, Mont., hit a record high of 99 degrees Wednesday, and tied its record high of 97 on Friday.
  • Salt Lake City established a September record high on Thursday after hitting 102 degrees. The previous record was 100 degrees. On Friday, it set a Sept. 2 record high of 100, the 29th day this year to reach 100 degrees in the Utah capital; the previous record was 21 times last year, as well as in 1994 and 1960.
  • Helena, Mont., hit 97 degrees Thursday, breaking the record of 96 set in 1955.
  • In Southern California, Burbank and Anaheim established records for the entire month of August on Wednesday as the mercury soared to 112 and 106.
  • Yakima, Wash., broke a record of 97 degrees set in 1949 when the city hit 98 on Wednesday.
  • Seattle and Portland set record highs of 90 and 100 degrees, respectively, on Tuesday.

Continued record-setting warmth is probable in the coming days, with the heat reaching a dangerous crescendo Tuesday. The National Weather Service warned that “extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities over the holiday weekend.”

Some of the hottest weather will be found in California’s Central Valley, including Sacramento, where highs could hit 110 degrees Monday and Tuesday. That would beat records of 108 and 109 set in 1988 and 2020, respectively.

Sacramento has already had three-dozen days at or above 100 degrees this year, and will probably reach the record of 41 days by the middle of next week.

Redding, Calif., is predicted to see highs of 109 both Monday and Tuesday, and even downtown Los Angeles should climb to about 103 degrees Sunday.

The only place to adequately beat the heat in California will be along the immediate Pacific coastline, such as the San Francisco Bay area, where comparatively manageable highs in the upper 70s to near 80 are expected.

There’s even a chance that Death Valley, Calif., could meet or exceed its record of 125 degrees, which would be the hottest ever observed there during the month of September. If Death Valley nicks 126 degrees, it would tie a global record for the month of September.

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Early outlooks hint that, after a brief tempering of the heat dome after Wednesday, a resurgence of heat in the western United States could be in the cards. It may even last until mid-September.

The heat is fueling wildfires in several Western states, exacerbating parched conditions brought on by years of drought stress and unusually hot weather this summer.

On Friday, multiple blazes erupted in Northern California. The Mill Fire, near the town of Weed, burned nearly 4,000 acres while destroying structures and injuring several people. Just 10 miles northwest of Weed, the Mountain Fire burned through nearly 1,500 acres.

The Cedar Creek Fire near Eugene, Ore., also exploded Friday, one of several forest fires actively burning in the state. Wildfires are also spreading in Idaho, where numerous temperature records fell this past week.

Conditions are predicted to worsen as the heat wave peaks over the Labor Day weekend.

Gusty winds expected Saturday could also lead to the rapid spread of new and existing fires.

The Weather Service’s Storm Prediction Center is warning of “critical fire weather” in Northern California, Nevada and Oregon as an upper-level trough passes through the region. Red flag warnings for high fire danger have been issued in several states, from California to Washington, Idaho and Montana.

The forecast is particularly concerning for California, where scorching temperatures this weekend will send vegetation to “ultra-flammable” levels, according to a forecast for Northern California from the National Interagency Fire Center’s Predictive Services. Periods of wind, combined with warm nights and low humidity, would further challenge firefighters who are already working through dangerous heat.

“Fires that become well established will spread through all fuel types with near total consumption the next several days,” another forecast for Southern California says.

Carlos Molina, a meteorologist with the National Weather Service in Hanford, Calif., said that soaring temperatures of up to 107 degrees would reach into the foothills of the Sierra Nevada, a popular destination for visitors to national forests and parks, including Yosemite. While the Sierra did receive moisture from monsoon storms this summer, coverage was spotty and generally only ranged from a half inch to an inch, he said.

“The fire danger is extremely high at the moment,” he said. “It’s bone-dry out there.”

Ignitions tend to spike during holiday weekends because more people are outdoors.

This weekend, travelers will be exposed not only to serious heat risk but also to increased wildfire risk. On Labor Day weekend in 2020, campers and hikers in the Sierra Nevada were airlifted to safety after they became trapped by the explosive Creek Fire, which broke out amid record-shattering heat in the state.

Climate change has intensified wildfire risk because a warmer atmosphere can more easily pull water from soils and plants. Studies have shown that human-caused climate change is a major contributor to increased vegetation dryness and burned area in the western United States, particularly in forests.

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