SLO County may be in a typical winter dry spell, but there is still a chance for rain

We may have entered the typical mid-winter dry spell, which historically lasts for a few weeks, even during the wettest years.

January dry spells are common and often produce an interesting weather pattern switch between the beaches and the coastal and inland valleys.

The interior valleys are frequently hot and dry in summer, while the beaches are socked in with fog and mist. Beach temperatures can be more than 50 degrees cooler during the afternoon than in the inland valleys.

However, the opposite can occur at this time of the year. As the Santa Lucia (northeasterly) winds blow through the coastal canyons and passes toward the beaches, they dry and warm the airmass, leaving behind clear skies. A terrible cousin of coastal fog, “Tule Fog” often develops in the San Joaquin Valley and can persist for days.

With that said, a weak cold front was forecast to move through the Central Coast on Saturday night into Sunday morning with increasing clouds, gentle variable winds, and heavy drizzle or light rain, primarily to the coastal regions. Rainfall amounts will remain below 1/10 of an inch, with snow levels dropping to 4,000 feet. In the wake of this low-pressure system, fresh to strong (19 to 31 mph) northwesterly winds and partly cloudy skies will follow on Sunday afternoon and night.

Increasing high pressure over the Great Basin will produce a pattern of moderate to fresh (13 to 24 mph) Santa Lucia (northeasterly) winds during the night and morning, decreasing and shifting out of the northwest during the afternoon starting on Martin Luther King Jr. Day (Monday) and continuing through Thursday morning.

This pattern will produce warmer temperatures and mostly clear skies, except for pockets of low marine clouds that will hug the coastline during the evening.

High temperatures will reach the low to mid-60s throughout the region, with overnight lows dropping to the high 30s in the inland valleys (Paso Robles) and low 40s in the coastal valleys (San Luis Obispo) and along the beaches. On Wednesday, temperatures could reach the low 70s along the beaches and coastal valleys.

Another weak cold front is forecast to move through the Central Coast on Thursday night into Friday with gentle variable winds and a chance of rain showers, followed by moderate to fresh (13 to 24 mph) northwesterly winds and marine low clouds on Saturday into next Sunday.

Surf report

A 6- to 8-foot northwesterly (290-degree, deep-water) swell (with an 8- to 16-second period) is forecast along our coastline on Sunday, decreasing to 4- to 6-feet (with an 8- to 17-second period) on Monday through Thursday.

A 3- to 5-foot westerly (275-degree, deep-water) swell (with an 8- to 13-second period) is expected on Friday into Saturday.

Seawater temperatures will range between 54 and 56 degrees through Thursday, increasing to 57 to 59 degrees on Friday through Saturday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

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