SLO County weather forecast: Big waves, light rain headed to Central Coast

Monday is expected to have some showers, but not the heavy rain that was initially forecasted.

Last week, a 991 millibar low-pressure system and associated cold front was going to produce gale-force southerly winds and heavy rain on Monday.

However, over the last 48 hours, the models now indicate the storm will take a more northerly track and the cold front will significantly weaken by the time it arrives along the Central Coast. As a result, much less rain is expected.

Consequently, the main weather story will be the large waves along the coastline this week.

A dissipating cold front will produce gentle to moderate (8 to 18 mph) northwesterly (onshore) winds which will allow the marine layer with areas of fog, mist and drizzle to develop in the coastal regions on Sunday. Along with the marine layer, there will be variable mid to high-level clouds.

A low-pressure system will move into Northern California and the associated cold front will produce gentle to moderate (8 to 18 mph) southerly winds and drizzle or light rain on Monday.

Total rainfall amounts are forecast to remain below a tenth of an inch in most Central Coast locations.

Fresh to strong (19 to 31 mph) and at times gusty Santa Lucia (northeasterly) winds are forecast on Tuesday into Wednesday morning. These winds will produce mostly clear skies, but also areas of dense ground fog in the coastal and inland valleys during the night and morning.

Another weak cold front will produce gentle to moderate (8 to 18 mph) northwesterly winds, increasing clouds and areas of mist and drizzle on Wednesday night into Thursday morning, followed by moderate to fresh (13 to 24 mph) Santa Lucia (northeasterly) winds and dry and clear skies on Thursday afternoon and night. There is a chance of rain on Friday; otherwise, dry weather is expected next Saturday and Sunday.

Surf report

A 921-millibar storm developed on New Year’s Eve near the Aleutian Islands. This was the lowest atmospheric pressure ever recorded in the North Pacific Ocean.

Long-period waves, also called forecast forerunners, from this mid-latitude cyclone with intervals of more than 28 seconds will arrive along our coastline Sunday night, increasing to 9 to 11 feet (with an 18- to 20-second period) on Monday. This swell will peak at 14 to 16 feet (with a 16- to 18-second period) on Tuesday, decreasing to 8 to 10 feet (with a 15- to 17-second period) by Wednesday. Note: Swell heights will be higher at the offshore buoys and along the northwesterly facing beaches.

A 12- to 14-foot northwesterly (295-degree, deep-water) swell (with a 14- to 25-second period) will arrive along our coastline on Thursday, increasing to 12 to 14 feet (with an 18- to 20-second period) Friday. This swell will decrease to 10 to 12 feet next Saturday and Sunday.

Seawater temperatures will range between 54- and 57-degrees next Sunday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

Please remember, if you go the coast to watch those waves, never turn your back on the ocean. Many people have thought they were far enough from the surf to be safe, but some of those waves can surge more than 150 feet up the beach. Many people over the years have been killed along the California Coastline after being swept off rocks by a wave. Also, stay physically distant from others, wear a mask, and remain situationally aware of your surroundings.

This story was originally published January 3, 2021 at 5:00 AM.