Millions in the West will face a potentially deadly heat wave this week, the second in as many weeks.
The calendar hasn’t even turned the page to the official start of summer yet, and already, the National Weather Service has issued Excessive Heat Warnings and Heat Advisories across California’s Central Valley and the Desert Southwest. The danger starts Monday for Sacramento. It then expands to Las Vegas and Phoenix on Tuesday and Wednesday, with Phoenix staying in the danger zone through Thursday.
“Dangerously hot conditions. Afternoon temperatures 105 to 112 expected,” warned the National Weather Service’s Phoenix office. “Overexposure can cause heat cramps and heat exhaustion to develop and, without intervention, can lead to heat stroke.”
The NWS issues Excessive Heat Watches when the heat index, or feels-like temperature, is forecast to reach dangerous territory in the next 24-72 hours. The watch turns into a warning 12 hours before and during “extremely dangerous heat conditions.” In general, the NWS looks for the heat index to hit or exceed 105 degrees for at least two days and overnight air temperatures that aren’t forecast to drop below 75.
This comes on the heels of last week’s record-breaking heat wave.
On June 6, Las Vegas tied its all-time earliest record of 110 degrees. The next morning, the city set a record-warm low temperature. Bishop, California, also shattered its previous record-warm low temperature by 7 degrees, according to the NWS.
Both Las Vegas and Phoenix are already struggling to prevent a repeat of the exceptionally deadly summer of 2023. According to the Southern Nevada Health District, heat-related deaths soared to 294 in 2023, a 78% increase from 2022.
Officials found that 645 people died of heat-related illnesses across the Phoenix metro area in 2023. That was over 50% more deaths than the previous year, which set a record for the number of heat deaths.
FOX Weather is tracking the heat wave, which starts in earnest Monday.
Monday
California’s Central Valley is under Excessive Heat Warnings and Heat Advisories. Sacramento’s average high is 86 degrees, but on Monday, the mercury will hit 96, and by Tuesday, it will top out at 103.
Fresno and Bakersfield are expected to hit 105 degrees on Tuesday. Their average highs are 89 and 90, respectively.
Tuesday
Tuesday will be the hottest day for California, and the heat expands across Arizona and Nevada.
Las Vegas, which averages a high of 98 degrees this time of year, will be 10 degrees hotter than average. Everyone outdoors on Wednesday will swelter in 109-degree heat. Thursday cools down, but not by much, with FOX Weather forecasting a high of 106 degrees.
The NWS has placed both Sacramento and Las Vegas in a Level 3 out of 4, or “major” threat, for heat-related impacts. NOAA recently rolled out its index called HeatRisk nationwide.
“This level of heat affects anyone without effective cooling and/or adequate hydration,” NOAA stated. “Impacts likely in some health systems, heat-sensitive industries and infrastructure.”
Wednesday
Arizona’s hottest temperatures are forecast on Wednesday and Thursday. Although the state is usually warm this time of year, the NWS said this week’s temperatures are “dangerously hot” even for the Valley of the Sun.
The average high for Phoenix is 103 degrees, but Wednesday is forecast to hit 111. Tucson, which is usually around 100 this time of year, heads to 109 degrees.
Fresno in California, Las Vegas, Phoenix and Tucson are under a major, or Level 3 of 4, risk for heat-related impacts, according to NOAA’s HeatRisk.
Thursday
Excessive Heat Warnings and Heat Advisories should expire by Wednesday for California but continue through Thursday evening for parts of Arizona and Nevada.
Phoenix, Tucson, Las Vegas and Fresno drop to a moderate, or Level 2 of 4, HeatRisk.
“This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration,” stated NOAA. “Impacts possible in some health systems and in heat-sensitive industries.”