Picnic Weather : Labor Day Weekend Forecast: It’ll Be Hot but Not So Humid

Southern California was hot and sticky Thursday, but the National Weather Service said the long Labor Day weekend will be a lot more comfortable.

Mainly, the forecasters explained, it will be drier.

High temperature in Orange County on Thursday was a warm-but-endurable 89 degrees in Santa Ana, while it reached 74 at Newport Beach.

If it seemed hotter, meteorologists explained that this was because the relative humidity ranged from a soppy 73% overnight to a still-pretty-soppy 32% in early afternoon.

Shifting Eastward

But the weather service said that should begin to change today, when a thermal trough of low pressure now centered at Yuma will begin shifting gradually eastward. This will allow a drier air mass to move into the Southland during the daytime, though higher pressure offshore will be able to force marine moisture across the coastline at night to give us the usual morning low clouds and fog.

Today’s forecast calls for temperatures from the upper 60s at the beaches to mid-80s in the inland areas, with relative humidity dropping to the high teens. And even drier conditions are expected Saturday, Sunday and Monday.

The beach forecast was also encouraging: Surfers, yachtsmen and even surf fishermen had to move with considerable caution Thursday as high waves associated with Hurricane Javier continued to pound south-facing beaches with six- to 10-foot surf, and the Coast Guard issued advisories for high surf and swells inshore with seven-foot seas farther out.

But Javier was weakening rapidly, and meteorologists said things should be much calmer through the weekend, with surf running three to four feet in most places, a 10- to 15-m.p.h. sea breeze each afternoon and water temperature in the mid-60s.

Offshore Swells

Sailing conditions should be better too, forecasters said, though offshore swells should continue to run to seven feet or more overnight, gradually diminishing today and Saturday as afternoon winds die from 25-knot gusts to 15-knot northwest breezes offshore and to 10- to 15-knot west to southwest winds inshore.

Mountains and deserts will continue chancy: Brief but violent thunderstorms continued to strike the area Thursday and, while the weather service said this activity should be on the wane today, forecasters said occasional thunder, lightning, wind and rain can be expected through Saturday.

High temperatures at San Bernardino and San Gabriel mountain resort levels were expected to be in the mid-70s to low 80s through Monday, with slightly cooler conditions in the Sierra.

The northern deserts were told to be ready for highs to 100, and the southern desert areas braced for highs above 110 degrees.

West winds to 25 m.p.h. were forecast for the San Francisco area today and Saturday, with morning low clouds clearing before noon and temperatures to the upper 60s.

Las Vegas Outlook

Las Vegas was braced for afternoon and evening thunderstorms today and Saturday, with temperatures well above 100 degrees, and a slow rise expected to continue through Monday.