SLO County weather forecast: Scattered rain showers expected this week

The last time Diablo Canyon recorded measurable rain was on Dec. 29, 2021, 53 days without any rain at the peak of our rainfall season. That is the longest streak without any precipitation in January and February at the power plant. This week will see a transition from a primarily Santa Lucia (offshore) wind condition to a northwesterly (onshore) wind situation which will allow the marine layer with areas of fog and mist to develop in the coastal regions. Along with the marine layer, scattered rain showers are expected on Tuesday and Wednesday.

A low-pressure system will move southward toward the Central Coast from the Pacific Northwest later Sunday into Monday. It will bring fresh to strong (19 to 31 mph) northwesterly winds on Sunday, cooler temperatures and low marine clouds with areas of fog and mist. Sunday’s high temperatures will range between the mid to high-60s.

Strong to gale-force northwesterly winds, increasing clouds and cooler temperatures are forecast on Monday, with most Central Coast locations only reaching the low-60s.

As this low-pressure system moves through the Central Coast on Tuesday into Wednesday, it will continue to produce strong to gale-force (25 to 38 mph) northwesterly winds and partly to mostly cloudy skies with scattered rain showers. At this time, rainfall amounts will remain below a 10th of an inch. High temperatures on Tuesday and Wednesday, we’ll only reach the mid-50s. There will also be a slight chance for thundershowers focused in the San Joaquin Valley and far eastern San Luis Obispo County. The highest precipitation totals will be in central and southern Sierra Nevada, where 3 and 6 inches of new snow could accumulate above 3,500 feet.

Clearing skies on Thursday and Friday will allow overnight temperatures to drop to the mid-20s in the inland valleys (Paso Robles) and low-30s in the coastal valleys (San Luis Obispo), with frost possible throughout the Central Coast. Daytime highs will reach the low to mid-60s with fresh to strong (19 to 31 mph) afternoon northwesterly winds and areas of marine low clouds and fog in the coastal regions.

The longer-range forecast models suggest a return of southerly winds and wet and unsettled weather by March 1 into the following week.

Surf report

Increasing northwesterly winds along the Northern and Central California coastline will generate a 5- to 7-foot northwesterly (310-degree, deep-water) sea and swell (with a 5- to 14-second period) on Sunday afternoon and night, building to 10- to 12-feet (with a 5- to 12-second period) on Tuesday through Wednesday.

Decreasing swell conditions are expected on Thursday into the following weekend.

Seawater temperatures will range between 54 and 56 degrees through Sunday, decreasing to 51 to 53 degrees on Monday into Wednesday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

Trees that fall or grow into power lines can cause outages or serious hazards. We provide a broad range of information and services to prevent outages and accidents. Please visit www.pge.com for information.

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.

This story was originally published February 20, 2022 at 5:00 AM.