LOS ANGELES — A potentially record-shattering heat wave has started to envelop the Southwest, threatening to bring temperatures of more than 120 degrees to parts of Arizona and California this week.
People in places like Palm Springs and Phoenix are used to seriously high temperatures, but 120 degrees is rare. Officials are warning residents about the need to keep hydrated, and opening cooling centers and public pools.
Strong high pressure building over Western states caused the hot onslaught.
Officials warned of excessive heat across southern portions of Arizona and Nevada, and throughout the 450-mile length of California’s Central Valley. Almost the entire Golden State is expected to simmer above normal temperatures, easing just short of the coast.
With up to 122 on the horizon, Palm Springs will have cooling centers in community buildings and libraries. In Phoenix, the city and nonprofit groups are planning water stations to help the homeless and others.
Palm Springs temperatures have soared above 120 several times, most recently hitting 122 on June 29, 2013.
The National Weather Service in Phoenix said the last time the mercury topped 120 there was in 1995 — at 121. The record is 122 degrees, set on June 26, 1990.
In California, forecasters said prolonged heat would make snow melt faster in the Sierra Nevada, where massive winter storms coated peaks after years of drought. Waterways could flood, with vacationers warned to be cautious near streams.
In Southern California, inland valleys, mountains, and deserts are likely to bear the brunt of the heat wave. Other parts of California, ironically, are still clearing snow from mountain roads.