Heatwave in Western US continues this week after breaking hundreds of records
Heatwave in Western US continues this week after breaking hundreds of records

A historically intense and long-lasting heat wave in the Western United States, which has set hundreds of records from Washington to Arizona, will continue to plague the region for several more days, with the first signs of at least modest relief not appearing until late next weekend.

Last weekend, astonishingly hot weather brought record temperatures of 48 degrees Celsius in Redding, California, and even 49 degrees Celsius in Las Vegas.

Heat warnings are in effect for most places west of the Rocky Mountains for days to come. California, Nevada, Oregon and Washington state are almost entirely affected. Extreme heat warnings – the highest warning level – apply to Boise (Idaho), Fresno (California), Las Vegas (Phoenix), Portland (Oregon) and Reno (Nevada), among others.

The National Weather Service’s heat risk scale (0 to 4) is expected to remain at its two highest levels across much of the region.

The greatest heat is expected in Central and Southern California over the next few days, but Washington, Idaho and Utah will also be affected by unusually high temperatures. Things could improve somewhat by Sunday.

“The multi-day duration and record high nighttime temperatures will continue to cause heat stress in people without adequate cooling and hydration,” the National Weather Service wrote early Monday.

The most remarkable heat records to date

Day after day, heat at extreme altitudes has produced staggering numbers. These are the three most significant heat records set since Friday:

  • Las Vegas – 120 degrees as the highest temperature on Sunday, breaking the old record of 117 degrees that had been set for several years.
  • Palm Springs, California – Friday’s maximum temperature was 124 degrees, breaking the old multi-year record of 123 degrees.
  • Redding, California – The highest temperature on Saturday was 119 degrees, breaking the old record of 118 degrees set on several days, including Friday.

Other places in California that reached at least all-time highs include Barstow (118), Bishop (111), Fresno (115), Lancaster (115), Twentynine Palms (118) and Ukiah (117).

In addition, hundreds of calendar day records were set, as far away as Seattle in the USA, where temperatures reached 93 degrees Celsius on Sunday, surpassing the previous mark of 90 degrees. Heat records were also set in western Canada.

Here are some other notable maximum temperatures reached in recent days:

  • Parker, Arizona – 124 degrees
  • Blythe, California – 123 degrees
  • Needles, California – 122 degrees
  • Laughlin, Nevada – 120 degrees
  • Phoenix – 118 degrees
  • Palmdale, California – 115 degrees
  • Sacramento – 112 degrees
  • Medford, Oregon – 112 degrees

Death Valley, California, saw its highest temperatures since late last week, reaching 129 degrees on Sunday, following a high of 128 on Saturday. These are both calendar-day records and very close to the world record of 130 degrees (based on reliable modern records; a 1913 measurement of 134 degrees is disputed). Highs will remain at 130 degrees throughout the work week, with 129, 130, 131, 131, 129, 127 and 125 degrees expected over the next seven days.

From California to Washington, numerous heat records are forecast for Monday, extending eastward to Idaho on Tuesday and Wednesday. By Thursday and Friday, record temperatures will retreat a little further south, focusing on California’s Central Valley and the desert southwest.

Highs between 100 and 120 degrees Celsius will continue to be common in much of California and neighboring states. In the hottest desert areas, temperatures will exceed 120 degrees.

In Las Vegas, temperatures may drop a few degrees on Monday compared to Sunday, but temperatures could climb back into the 40s Tuesday through Thursday. In Phoenix, temperatures will also be around 46 degrees for most of the work week.

By Sunday, temperatures in much of the West could drop just enough to be safely below record highs.

While the heat in the west may ease briefly by Sunday, there are few signs of a major change in the overall weather situation.

Computer models suggest that the heat dome – or zone of intense high pressure – responsible for the sweltering temperatures will mostly stay in place, shifting only slightly eastward toward the Four Corners region. This small shift may mean that California is only very hot, rather than record-breakingly hot.

Long-range models indicate that the heat dome could again settle near the west coast in the last third of July.

By Everly