Sin City soared to a searing 117 degrees Saturday, matching its highest temperature ever observed amid a punishing heat wave that will continue in the West into early this week.

More than 30 million people are under excessive heat warnings and heat advisories Sunday, including most of interior California, much of Nevada, western Arizona and Utah, southeast Oregon and southern Idaho. Temperatures are predicted to be comparable to those on Saturday, when many long-standing records fell.

Extreme heat will continue in the region through Tuesday or Wednesday, though the intensity will slowly ease.

Las Vegas was among several locations that matched or topped all-time highs in the Southwest on Saturday. St. George, about 120 miles northeast of Las Vegas in southwest Utah, reached 117 degrees, preliminarily tying Utah’s all-time temperature record.

Utah is potentially the third state to match an all-time mark in two weeks. Oregon and Washington state equaled their all-time highs during the “unprecedented” Pacific Northwest heat wave at the end of June.

In addition to Las Vegas and Utah, several other locations reached historically significant temperatures on Saturday, including:

Amid the blistering heat on Saturday, California’s power regulator and Nevada Energy asked residents to conserve energy by adjusting thermostats and reducing use of appliances.

The heat wave afflicting the West is the third in three weeks, after the event in the Pacific Northwest at the end of June and a record-setting blast in the Southwest in the middle of the month; together, they vaulted the nation to its hottest June on record. The heat wave in the Pacific Northwest was made at least 150 times as likely by human-caused climate change, according to a panel of scientists.

How hot will it get Sunday?

The National Weather Service in Las Vegas wrote that temperatures are again likely to “rival or challenge all-time records.”

“Today is probably the last day where reaching or exceeding the all-time Las Vegas records is possible, with slight cooling expected Monday as heights begin to slowly decline,” it wrote. “Similarly, best chance for 130 or higher in Death Valley will be today, before chances dwindle next week.”

While temperatures in California’s Central Valley may fall shy of all-time records, the Weather Service is still warning of dangerously hot conditions. “Very high heat risk is expected again today due to the combination of warm overnight lows and hot afternoon temperatures,” wrote the Weather Service in Sacramento.

Here are predicted high temperatures at some major population centers:

  • Redding: 114
  • Chico: 111
  • Sacramento: 107
  • Stockton: 106
  • Modesto: 107
  • Fresno: 112
  • Bakersfield: 111

Areas near the coast will be substantially cooler. The forecasts for highs in San Diego, Los Angeles and San Francisco are predicted to be 74, 87 and 68, respectively.

Temperatures may vary drastically between coastal locations and those just slightly inland. On Saturday afternoon, for example, it was 115 degrees at Paso Robles Airport near San Luis Obispo, but at Diablo Canyon, 34 miles away, it was only 58.

Gradual relief during the workweek and some monsoon rains

Temperatures on Monday and Tuesday will remain above normal in the Southwest but will back off gradually from record-setting territory.

The heat dome, or zone of high pressure responsible for the sweltering temperatures, is forecast to weaken while the summer monsoon strengthens. This will bring some much-needed rain in Arizona, New Mexico, Nevada and western Colorado, all of which are enduring extreme to exceptional drought conditions.

However, long-range computer models show potential for another intense heat wave in the West building by next weekend, focused on the central and northern Rockies, which could bring more exceptionally high temperatures.