Forget winter weather: SLO County’s forecast calls for warm, windy days

So far this month, I’ve noticed many visitors from the San Joaquin Valley enjoying the sunshine along the Central Coast, and here is why.

Weather stations across California’s Great Central Valley are reporting temperatures stuck in the low- to- mid-40s beneath persistent Tule fog over the past few weeks. In fact, temperatures there have varied by only a few degrees between day and night for most of the month.

Meanwhile, along the Central Coast, daytime temperatures have been climbing into the upper 70s and low 80s — nearly 10 degrees above normal for December.

A weak, 1,015-millibar, transitory, low-pressure system along the Central Coast will bring gentle to moderate (8 to 18 mph) southerly winds on Saturday, allowing low marine clouds to form in coastal regions with cooler daytime temperatures but warmer overnight lows under partly cloudy skies.

By Sunday, a 1,020-millibar Eastern Pacific High located about 600 miles to the southwest, combined with a 1,022-millibar high over the Great Basin, will generate gentle to moderate (8 to 18 mph) Santa Lucia (northeasterly) winds during the night and morning.

These overnight winds will strengthen to moderate to fresh (13 to 24 mph, with gusts up to 30 mph) levels on Monday through Tuesday. The downslope winds should be strong enough to push the marine layer out to sea, leaving behind clear skies, crisp mornings and mild afternoons.

During this period, inland valleys such as Paso Robles will see nighttime and early-morning lows in the mid-30s, warming into the low to mid-70s during the afternoon.

Coastal valleys, San Luis Obispo and the beaches can expect overnight lows in the mid-40s with afternoon temperatures in the mid-70s.

Fresh to strong (19 to 31 mph) northwesterly winds are expected Wednesday through Friday, diminishing by the following weekend. This surge of marine air is forecast to bring warmer overnight lows but cooler daytime highs, along with low marine clouds and pockets of fog or mist overnight.

Long-range models currently indicate that a 1,007-millibar, low-pressure system will slide southward along the California coast on Christmas Eve, Christmas Day and the day after.

This system may produce southerly winds and rain, with snow in the higher elevations.

As always, long-range forecasts are subject to change.

Surf report

A 4- to 6-foot northwesterly (290-degree, deep water) swell (with an 8- to 13-second period) is forecast along our coastline through Saturday, decreasing to 2 to 3 feet (with an 8- to 12-second period) on Sunday through Tuesday morning.

Increasing northwesterly winds will generate a 5- to 7-foot northwesterly (315-degree, deep water) sea and swell (with a 5- to 14-second period) starting on Tuesday afternoon and continuing through next Saturday.

Seawater temperatures will range between 60 and 63 degrees through Tuesday, decreasing to 58 degrees and 60 degrees on Wednesday through next Saturday.

On this date in weather history

1924: The temperature at Helena, Montana, plunged by 79 degrees in 24 hours and 88 degrees in 34 hours. The mercury dropped from 63 degrees to 25 degrees below zero. At Fairfield, Montana, the temperature plummeted by 84 degrees in just 12 hours, from 63 at noon to 21 degrees below zero at midnight. (David Ludlum)

2010: A rare tornado struck the small town of Aumsville, Oregon, tearing roofs off buildings, hurling objects into vehicles and homes and uprooting trees. No one was injured, but the destruction left behind was severe. The National Weather Service classified the tornado as an EF2 with wind speeds of 110 to 120 mph. The tornado’s damage trail was 5 miles long and 150 yards wide. Fifty houses in Aumsville and the surrounding county area were affected, with 10 of them being unsuitable for occupancy. (KATU)

2017: A dry air mass combined with clear skies allowed the Paso Robles Municipal Airport to break two temperature records in less than nine hours the day prior: a record low of 22 degrees followed by a record high of 73 degrees for a 51-degree temperature swing! The San Luis Obispo County Regional Airport hit 83 degrees, breaking its record for the third day in a row. The previous record of 81 degrees was set in 1988.

2020: A cold front dissipated as it traveled from north to south through San Luis Obispo and Santa Barbara counties. The greatest amount of rain occurred in the San Simeon and Cambria area. The Walter Ranch in the Santa Lucia Mountains above Cambria recorded the most rain at 0.81 of an inch.

2021: The southerly winds at the Diablo Canyon Meteorological Tower reached 45 mph sustained with gusts up to 55 mph at 7:15 p.m. Heavy rainfall was reported throughout the Central Coast with the frontal passage. Camp San Luis Obispo reported the most rain at 7.44 inches, while Rocky Butte saw 5.7 inches. See Canyon recorded 6 inches of rain, and Santa Barbara, La Cumbre South had 3.5 inches.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

SUNDAY: 37, 72

MONDAY: 36, 73

TUESDAY: 37, 73

WEDNESDAY: 39, 68

THURSDAY: 49, 65

FRIDAY: 43, 69

SATURDAY: 38, 70

SUNDAY: 37, 72

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUNDAY: 48, 72

MONDAY: 47, 76

TUESDAY: 47, 75

WEDNESDAY: 48, 68

THURSDAY: 55, 67

FRIDAY: 51, 70

SATURDAY: 49, 71

SUNDAY: 48, 73

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