A surfer attempts to beat the heat in San Diego on Sunday. (Jim Grant via Twitter)

Temperatures shot up over 110 degrees in Southern California on Friday, obliterating all kinds of long-standing heat records, and the lights went out for tens of thousands of customers. Californians were powerless, without air conditioning, in the hottest weather many had ever experienced.

Climate scientists have known this was coming, and it may only be the beginning.

“We studied this a long time ago . . . now our projections are becoming reality,” tweeted Katharine Hayhoe, a climate scientist at Texas Tech University.

In 2006, Hayhoe and colleagues published the study “Climate, Extreme Heat, and Electricity Demand in California” in the Journal of Applied Meteorology and Climatology.

“Over the twenty-first century, the frequency of extreme-heat events for major cities in heavily…