Extreme Heat Forecast for Western U.S. May Kick Off Sweltering Summer. Here’s the Outlook

A significant early-season heat wave headed for western North America is threatening to deliver stifling temperatures that could break records, prime the landscape for wildfires and kick off a sizzling summer.

A powerful high-pressure ridge, or heat dome, will bring unusually hot temperatures to the Golden State by the middle of this week before spreading into the Pacific Northwest and Southwestern Canada, according to Daniel Swain, a climate scientist with UCLA. Temperatures could remain well above normal across much of the region for as long as 10 to 14 days.