West Coast's Winter to Close With Triple-Digit Temps

Winter is closing with a blast of summer across the West, with a powerful "heat dome" expected to topple March records from California to Colorado, per the Washington Post. Forecasters say temperatures could run up to 30 degrees above normal, with Los Angeles, Phoenix, and Las Vegas flirting with 100 degrees next week, and Salt Lake City and Denver likely to see record temperatures in the 80s. Climate scientist Daniel Swain called the outlook, following a less-intense wave of warming over the weekend, "truly extraordinary for March." Hundreds of high temperature records could be broken, per the Post. NOAA estimates 20 to 25 million people will face at least moderate heat risk, meaning health impacts are possible for vulnerable groups and those without cooling.

The early-season scorcher arrives on top of a historically warm US start to March and a winter marked by low snow and long-running warmth in much of the West. Utah's assistant state climatologist Jon Meyer warned the pattern is "the nail in the coffin" for an already grim snowpack; the state's reservoirs sit at about 40% capacity, and water cuts and tighter conservation are expected. Off Southern California, a strengthening marine heat wave—ocean temperatures up to 5 degrees above normal—will help lock in the warmth, especially at night, and is part of a trend of more frequent, longer-lasting marine heat events in a warming climate. In the East, "winterlike cold" returns next week, per CNN. Washington, DC, which saw a high of 84 degrees Tuesday, will see temps fall to the 40s.