Weekend Forecast Shapes Up Like, Well, a Summer Holiday

Forecasters said the weather for Southern California’s Independence Day weekend should be just about the same as the rest of the week:

Overcast mornings.

Bright, warm afternoons.

And long, cool evenings with more clouds gathering before midnight.

Steve Newman, meteorologist-spokesman for Earth Environment Service, a private forecasting firm based in San Francisco, said atmospheric currents “are subtle at this time of year, so changes in the weather are subtle, too.”

Which is just another way of saying “no change expected.”

An upper-level trough over the eastern Pacific is expected to keep a dry, southwest flow of air going at least until the middle of next week, rendering skies mostly clear but also encouraging an onshore flow of marine air to keep morning skies cloudy along the coast.

High temperature at Los Angeles Civic Center on Thursday reached 77 degrees, with relative humidity ranging from a low of 54% to a high of 90%, and forecasters agreed that it might be a few degrees warmer today. But not so much that you would know it without a thermometer.

Beaches are expected to be cool: afternoon highs from the mid-60s to the mid-70s, with surf two to four feet in most places, an afternoon sea breeze rising to 16 m.p.h. and ocean water temperature in the mid-60s.

Holiday yachtsmen who stick close to shore can expect westerly winds rising to 15 knots and two-foot seas in the afternoons from Point Conception to the Mexican border, while those who venture farther out should look for northwest winds gusting to 20 or 25 knots and three-foot seas combined with three-foot northwest swells in the afternoons.

Mountain skies should be clear, with temperatures to the upper 70s at resort levels, though the National Weather Service said the Sierra could see a few thundershowers before Monday.

High-desert temperatures are expected to pass 100 degrees most days, with low deserts a few degrees hotter, and forecasters said west to southwest winds could hit 25 m.p.h. at times in the afternoons and evenings.

The forecasters said Arizona’s holiday should be sunny and clear, with highs to the 80s in the mountains and to 110 degrees or more in the deserts. Las Vegas visitors can expect afternoon temperatures to 115 degrees, with local south winds gusting to 25 m.p.h.

Ensenada will get its share of late-night and early morning cloudiness, but skies should be sunny before noon, with temperatures in the idyllic 70- to 75-degree range.

San Francisco’s traditional morning fog and low clouds are expected to burn away by the afternoon at most inland locations, though they could persist along the coast. Temperatures are expected to range from the mid-60s to the mid-70s.