SLO County weather forecast: Expect ‘May Gray’ overcast skies until next weekend

After an extended period of gale-force northwesterly winds and mostly clear skies, a change in the weather pattern will occur this week with decreasing winds and a persistent marine layer (May Gray) in the coastal regions of San Luis Obispo County.

Fresh to strong (19 to 31 mph) afternoon northwesterly winds are expected on Sunday into Monday. These winds will allow the marine layer with areas of fog and mist to develop along the coastline during the night and morning, clearing during the afternoon.

Gentle to moderate (8 to 18 mph) northwesterly winds are expected on Tuesday through Thursday as a trough of low pressure moves over Central California. This system will produce overcast skies throughout the day with areas of fog and drizzle during the night and morning along the shoreline. Over this period, the beaches will range between the high-50s and low-60s, while the coastal valleys (San Luis Obispo) will see the mid-70s. The inland valleys (Paso Robles) will warm to the mid-80s under clear skies.

Strong to gale-force northwesterly winds, clearing skies and slightly warmer temperatures in the coastal regions are expected on Friday into next weekend.

Surf report

A 4- to 6-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) will level through Sunday.

A 6- to 8-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 11-second period) will develop on Monday, becoming a 5- to 7-feet swell on Tuesday.

A 3- to 5-foot northwesterly (285-degree, deep-water) swell (with an 8- to 11-second period) is forecast along the Central Coast on Wednesday, decreasing to 2- to 4-feet by Thursday.

Increasing northwesterly sea and swell is expected to start on Friday and continue through next Sunday.

Arriving from the Southern Hemisphere, a 1- to 2-foot (190-degree, deep-water) swell (with a 15- to 17-second period) will continue at this level through Monday.

Seawater temperatures range between 48 and 50 degrees though Monday, increasing to 51 to 54 degrees on Tuesday into Thursday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

Fog and drizzle are predicted this week. According to the California Highway Patrol, here are some tips for driving in foggy conditions:

▪ Drive with lights on low beam. High beams will reflect off the fog, creating a “white wall” effect.

▪ Reduce your speed and watch your speedometer. Fog creates a visual illusion of slow motion when you might be speeding.

▪ Avoid crossing traffic lanes.

▪ Travel with the driver’s window partially open. Listen for traffic.

▪ Watch for CHP pace cars to guide you.

▪ If your vehicle is disabled or you can’t continue, pull well onto the shoulder and turn off lights. Move away from your car. Consider postponing your trip until the fog lifts.

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.