Prepare for a major heat wave, Los Angeles.

Yeah, we know: Your calendar now says that it's fall. But the weather patterns of an Indian summer, mixed with our traditional, fall offshore winds, will create at least three days of blistering heat in Southern California starting on Sunday, with temperatures as high as 107 on Monday, the National Weather Service tells the Weekly.

Add to that fire danger and juicy surf:

Tropical storm Miriam off the Baja coast could generate some south swell while mixing with waes from the northwest, says NWS meteorologist Dave Gomberg.

That's not good for novices flocking to the coast.

But the real worry here is “fire danger,” he says.

Credit: Preston Thalindroma / Flickr

Credit: Preston Thalindroma / Flickr

A high pressure system over the Great Basin will push desert heat over the mountains and into the SoCal valleys and basin, goosing temps starting on Sunday, Gomberg says:

We're coming to the time of year where we're getting into Santa Ana wind season … It's taking warm, dry desert air and descending to Southern California.

Numbers on Sunday could hit 100 in the valleys and 95 downtown.

And then the real heat will hit:

On Monday and Tuesday look for possible record temperatures in the San Fernando and San Gabriel valleys — as high as 107.

The foothills and mountains will remain warm at night, with temps in the 70s, but things will cool down after dark Sunday through Tuesday for the rest of us, with numbers in the 60s, Gomber says.

And then the wave is over, hopefully, on Wednesday, when high pressure backs off and an onshore, Pacific flow returns.

However, temps could still reach 100 in the valleys that day.

In the meantime it could be a surfer's paradise with offshore winds (breezes is a better term, Gomberg says) and decent waves.

The weather service this afteroon was preparing a “special weather statement” to warn of next week's fire danger and heat.

[@dennisjromero / / @LAWeeklyNews]

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