Sultry October shaping up as our lost summer

Summer turned out to be a cooler than normal dud this year.

But October dressed up as summer this Halloween season.

With eight scorchers over 90 degrees this month, Los Angeles has been in the midst of the second-hottest October since 1877, according to climate records.

“It’s the summer we never had,” said William Patzert, a climatologist for the Jet Propulsion Laboratory in La Canada Flintridge.

The average daytime temperature in downtown Los Angeles this month has been 84.3 degrees, he said. September’s average high temperature was 83.2 degrees, according to the National Weather Service.

“In September we only had two days over 90,” Patzert said.

The warmest October in Los Angeles’ recorded history -- an average of 84.5 degrees -- was 1965, when Southern California was blasted by hot, dry Santa Ana winds. On Oct. 23 of that year, Los Angeles had a temperature of 100 degrees. In San Diego, firefighters were busy battling three blazes amid the October heat wave.

This October has also seen its share of wind-whipped brush fires, notably two huge blazes that burned dozens of San Fernando Valley homes.

The reason for the high temperatures is fairly predictable. Several high-pressure systems parked over the Southwest have compressed and heated the air cycling into the region. The resulting Santa Ana winds have not been powerful so far, but they have arrived early and with regularity, Patzert said.

“Every fall there’s a great race. Will the Santa Anas precede the rains or vice versa?” he said. “So far, the Santa Anas are ahead of the rains by at least five lengths.”

There’s a chance this month may fall to third place after October 1999, when the average daytime maximum temperature was 84.1. The reason is that temperatures may drop just enough in the last four days of October, said Stuart Seto, a weather specialist for the National Weather Service in Oxnard. But maybe not, he said.

“We may tie 1999,” Seto said.

At first, it looked like showers were on the way, but Seto said it looks as if the chances of rain this weekend are practically nonexistent. And that’s bad, climatologists say, because Southern California has been so dry for so long and the conditions are ripe for fires.

“We’ve had essentially eight months of no rain, and we’re having one of the driest falls,” Patzert said. “Either we’re getting our quota of Santa Anas out early or this is a preview of coming attractions, which is scary because right now there is no rain on the horizon.”

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hector.becerra@latimes.com

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Average highs for October

1965: 84.5 degrees

2008: 84.3 degrees*

1999: 84.1 degrees

*Through Monday

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Source: William Patzert, Jet Propulsion Laboratory