SLO County weather forecast: Overcast skies with pockets of mist and fog

A trough of low pressure along the California coastline will continue to produce onshore winds, below-normal temperatures, and mostly overcast skies with pockets of fog and mist during the overnight “May Grey,” with afternoon clearing through the end of the month. However, May Grey is not expected to transition to June gloom during the first week of June as fresh to strong (19 to 31 mph) northwesterly winds produce more clearing with slightly warmer temperatures.

A trough of low pressure will develop along our coastline on Sunday through Wednesday. This system will create gentle to moderate (8 to 18 mph) southerly winds, primarily overcast skies with partial afternoon clearing and below-average temperatures. Temperatures will reach the low-70s in the inland valleys (Paso Robles), the low to mid-60s in the coastal valleys (San Luis Obispo), and along the beaches.

This trough will move off to the south on Thursday. Consequently, fresh to strong (19 to 31 mph) northwesterly winds will develop during the afternoon through the following weekend and help to mix out the temperature inversion layer, leaving behind mostly clear skies and slightly warmer temperatures during the afternoon.

The long-range models do not indicate any rain for the Central Coast. However, scattered thunderstorms are expected in the Sierra Nevada Mountain range during the afternoon and evening.

Surf report

A 2- to 4-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) is expected along our coastline on Sunday through Tuesday, increasing to 3- to 5-feet on Wednesday.

Increasing northwesterly winds along the coastline will generate a 5- to 7-foot northwesterly (310-degree, deep-water) sea and swell (with a 5- to 12-second period) on Thursday through Friday.

Combined with this northwesterly sea and swell will be a 1- to 2-foot (215-degree, deep-water) southern hemisphere swell (with a 14- to 16-second period) on Saturday into Monday.

Seawater temperatures will range between 53 and 55 degrees through Sunday, increasing to 55 to 57 degrees on Monday through Wednesday as the currents flow northward.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

John Lindsey’s is a retired PG&E marin meteorologist. Email him at JohnLindseyLosOsos@gmail.com or follow him on Twitter at @PGE_John.