A showy surf, warm, dry weather and clear visibility are expected to deliver another summer-like January weekend when a mild Santa Ana blows in unseasonable weather today.
Following the hazy, humid weather kept cool by two weak cold fronts that moved through the county this week, an influx of warm temperatures and clear skies is expected to move in just in time for a sunny weekend.
According to the National Weather Service, a high-pressure system that was off the West Coast will reach southern Utah by today, setting up the Santa Ana condition that will send winds from the Salt Lake City area across the desert and mountains to Southern California.
The winds are not expected to be strong, forecaster Wilbur Shigehara said, but they should have the effect of stunting the breezes off the ocean and stopping the onshore flow of moisture.
Humidity that was a high 75% at 4 p.m. Thursday is expected to drop to 40% by this afternoon as the Santa Ana condition begins.
Spectacular waves are expected at the beaches, with a high 10-foot surf forecast for west-facing beaches.
A storm north of Hawaii generated the waves that have been traveling here over the last couple of days, Shigehara said. The surf is expected to be highest today and may diminish slightly over the weekend.
A small-craft advisory will be in effect for rough seas at harbor entrances through Sunday.
Shigehara said beachgoers and boaters are advised to use caution and common sense during the period of high surf.
"It will be nice weather, but the waters might be hazardous," he said.
Tides will be average through the weekend, with a 6.1-foot high tide at 7:42 a.m. today, and 6.2-foot tides at 8:17 a.m. Saturday and at 8:52 a.m. Sunday.
Aside from dense fog this morning, forecasters predict clear weather both day and night at least through Sunday and probably into early next week.
Visibility, which was only about three miles at the coast Thursday, is expected to improve dramatically, forecasters said.
Smog levels are expected to continue to be moderate. According to the San Diego Pollution Control District, which marks 100 as the upper limit for clean air on a Pollutant Standard Index, measurements expected for today are: 75 in El Cajon and Oceanside, a relatively clean 59 downtown, a relatively dirty 92 in Del Mar, 84 in Escondido, 87 in Chula Vista and 84 in Alpine.
With dry weather forecast for the last weekend of the month, this January may wind up the fifth driest on record, forecasters said. A minuscule 0.01 of an inch of rain has been recorded at Lindbergh Field in a month that is normally the wettest of the year. January rainfall averages 2.11 inches.
Last January's rainfall was also below normal, at 0.52 of an inch.
Temperatures in all areas this weekend are expected to be 4 to 8 degrees above normal during the day, and lows should drop slightly under clear nighttime skies.
Highs at the beach should be in the high 60s through Sunday. Along the coastal strip, highs in the 60s today should reach the 70s by Saturday, and nighttime lows are expected to be in the 40s and low 50s.
Inland valley highs in the 68- to 74-degree range today may reach the 80s over the weekend.
Mountain highs are expected to be in the 48- to 58-degree range today and Saturday, with lows in the 20s and 30s. Desert highs should be in the 70s with lows in the 40s.