SLO County weather forecast: Fog along the coast and strong rip currents

This week’s upcoming weather looks to be uneventful and typical for late summer.

The marine layer with pockets of fog and mist will continue to develop in the coastal valleys and along the beaches during the night and morning, clearing during the afternoon as fresh to strong (19 to 31 mph) northwesterly afternoon winds develop along the coastline on Sunday and Monday.

The ridge of high pressure responsible for the warm to hot weather away from the ocean will weaken this Sunday into Monday and temperatures will decrease to the mid-90s in the inland valleys (Paso Robles) and high-70s in the coastal valleys (San Luis Obispo). The beaches will remain in the 60s, except along the southerly facing beaches such as Cayucos, Avila Beach and Shell Beach which will reach into the 70s on Sunday and Monday.

A trough of low pressure will develop off the coast on Tuesday through Friday resulting in gentle to moderate (8 to 18 mph) southerly to northwesterly (onshore) winds and a deep marine layer with pockets of fog and drizzle during the night and morning. Many of the beaches could remain mostly overcast throughout the day; however, a reverse clearing condition with the sun showing itself first along the shoreline could develop by Thursday. Naturally, high temperatures will cool to the mid-80s in the North County and mid-70s in the coastal valleys. The beaches will remain in the 60s.

The long-range models do not indicate rain or Santa Lucia (northeasterly) wind events over the next two weeks.

Surf report

A 980 millibar storm that developed in the Gulf of Alaska last Friday will generate a 4- to 6-foot northwesterly (300-degree, deep-water) swell (with an 8- to 16-second period) along our coastline on Sunday, increasing to 6 to 8 feet (with an 8- to 13-second period) on Monday into Tuesday. A 3- to 5-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) is forecast along our coastline on Wednesday through Friday.

Seawater temperatures will range between 55 and 58 degrees through Monday, gradually warming on Tuesday through Saturday. In fact, seawater temperatures may range between 58 and 62 degrees by Friday.

Arriving from the Southern Hemisphere: A 1- to 2-foot Southern Hemisphere (195-degree, deep-water) swell (with a 19- to 21-second period) is forecast to arrive along our coastline on Sunday. This swell will increase to 2 to 4 feet (with an 18- to 20-second period) on Monday and peak on Tuesday at 3 to 4 feet (with a 17- to 20-second period). This swell will decrease to 2 to 4 feet (with a 16- to 18-second period) on Wednesday into Thursday.

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

This week’s long-period Southern Hemisphere swell will produce heavy surge and strong rip currents. Please be careful if you’re heading to the beaches. Rip currents are generally narrow and swift-moving streams of water that flow from the beach, through the breaker zone, out to sea, then fan out behind the breakers and become quite diffused. If you find yourself in a rip current, swim parallel to the beach until you are out of the rip. Never try to swim against a rip, as you could become quickly tired and hypothermic in the cold waters of the Central Coast. The strength or location of the rip current is unpredictable. When they occur, they may be irregularly or evenly spaced along the beach; some of the rips may be weak while others can be quite strong.

John Lindsey’s is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.