Publication Date July 27, 2016

What is the heat dome and how does it affect California?

United States
A firefighter watches a wildfire near Placenta Caynon Road in Santa Clarita, Calif., Sunday, July 24, 2016. Photo: Ringo H.W. Chiu, AP

On July 24, at least 26 states had heat warnings or advisories in effect, stretching from California to New York. A day later, Washington was the only state in the lower 48 that did not see temperatures in at least the 90s. For much of the past week, the dome was centered over the Midwest, but it’s been growing and broadening its reach. Now, in California, the weather service warns the heat dome will create low humidity levels and extreme temperatures (110 degrees near Sacramento, for example) at least through the weekend.

That’s especially bad news for a state that has struggled with almost five years of intense drought resulting in precarious fire conditions. On Tuesday, acting California governor Tom Torlakson issued emergency proclamations for two fires burning in Los Angeles and Monterey counties. Temperatures in Southern California hit 101 degrees in the past two days, fueling the Sand Fire in Santa Clarita to overtake 57 square miles—bigger than the city of San Francisco. The Soberanes fire has burned more than 23,500 acres between Carmel and Big Sur and is now bigger than the size of Manhattan