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Environment & Science

Are Southern California heat waves getting more humid?




In this file photo, towers carrying electrical lines are shown August 30, 2007. This weekend will bring the kind of scorcher Southern Californians are used to — hot and dry with a chance of fires. But by next week we'll get hit with monsoonal moisture. Is this a trend?
In this file photo, towers carrying electrical lines are shown August 30, 2007. This weekend will bring the kind of scorcher Southern Californians are used to — hot and dry with a chance of fires. But by next week we'll get hit with monsoonal moisture. Is this a trend?
Justin Sullivan/Getty Images

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A major heat wave is set to hit Southern California this weekend, bringing with it dangerously hot conditions and an increased risk of wildfires.

A high pressure system settling over the region is so strong it's eliminating the marine layer, which would normally exert a cooling influence, according to Todd Hall, a meteorologist with the National Weather Service.

An excessive heat warning has been issued for the valleys and mountains until tomorrow night.

"We are looking at temperatures 10 to 15 degrees above normal for this time of year and in addition we already have dry conditions in place so that will be bringing us critical fire conditions for this weekend as well," Hall told KPCC.

Once we get through the weekend, however, we'll be getting a different sort of heat. Unlike the usual scorcher, this one will bring sticky heat.

"Humidity is going to get a lot stronger next week although the heat's not going to be quite as much," Alexander Gershunov, a research meteorologist with the Scripps Institution of Oceanography at UC San Diego, told Take Two. 

Historically California’s heat is very dry, will a cooling effect in the evening, but as a long-term trend humidity is rising in the region, Gershunov said.

"What we see in the statistics of heat waves over the past several decades is that they're getting more humid, so it's the nighttime temperatures that are increasing very, very strongly. Much more strongly than the daytime high," Gershunov said.

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