SLO County weather forecast: Expect clouds and lower temperatures across the Central Coast

John Lindsey/JohnLindseyLosOsos@gmail.com

Typically, the inland valleys (Paso Robles) see their warmest air temperatures of the year in July and August, while the coastal valleys (San Luis Obispo) are the hottest during September and the beaches in October. However, due to the lack of Santa Lucia (northeasterly/offshore) winds, except on Tuesday morning, the first week of October will see the beaches and many of the coastal valleys covered by a blanket of low marine clouds. This condition will keep temperatures relatively mild.

Persistent northwesterly (onshore) winds will allow the marine layer to move inland overnight with pockets of mist and drizzle, clearing from most areas during the late morning and afternoon. A few of the beaches may remain overcast throughout the day.

Sunday’s high temperatures will range from the low-60s at the beaches, the high-60s to the low-70s in the coastal valleys, and the mid-80s in the inland valleys.

Fresh to strong (19 to 31 mph) northwesterly winds are forecast along the coastline during the afternoon on Monday, shifting out of the northeast (offshore) and decreasing to moderate to fresh (13 to 24 mph) levels on Tuesday morning. These Santa Lucia winds should produce mostly clear skies and warmer temperatures along the beaches and in the coastal valleys.

Persistent northwesterly (onshore) winds on Wednesday through Saturday will allow the marine layer to redevelop and move inland overnight with pockets of mist and drizzle, clearing from most areas during the afternoon.

At this time, this weather pattern is expected to continue through next week as there are still no signs of continuous Santa Lucia (northeasterly/offshore) winds.

NOAA’s GFS (Global Forecast System) and the ECMWF (European Centre for Medium-Range Weather Forecasts) are advertising an early season low-pressure system developing off the Northern California coast in mid-October. This tempest could be strong enough to produce increasing southerly winds and rain showers along the Central Coast.

Surf report

Sunday’s 3- to 5-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) will remain at this level into Monday morning.

Fresh to strong (19 to 31 mph) northwesterly winds will generate a 3- to 5-foot (310-degree, deep-water) sea and swell (with a 5- to 12-second period) on Monday afternoon, increasing to 4- to 6-feet (with a 5- to 16-second period) on Tuesday through Friday.

A 1- to 2-foot Southern Hemisphere (210-degree, deep-water) swell (with a 15- to 17-second period) is expected along our coastline on Tuesday through Thursday, decreasing Friday.

Seawater temperatures will range between 57 and 59 degrees through Friday.

This Date in Weather History (October 2):

1882 - An early season windstorm over Oregon and northern California blew down thousands of trees and caused great crop damage in the Sacramento Valley. (David Ludlum)

1898 - A hurricane struck the Georgia coast washing away Campbell Island. (David Ludlum)

2015 - The PG&E Black Butte weather station on the Cuesta Grade reported Santa Lucia (northeasterly) winds of 31 mph sustained with gusts to 42 mph at 5 a.m. These Santa Lucia winds are producing areas of low clouds and fog in the North County, but clear, dry and warmer conditions in the coastal valleys and along the beaches due to katabatic heating.

2020 - The Lompoc Airport reached 100 degrees, breaking the previous daily record of 95° set on Oct 1, 1965. The Santa Maria Airport hit 102°, beating the old record of 100° set in 2012. Cal Poly reached 109 degrees, besting the old daily record of 107 degrees recorded on Oct. 1, 2012.

Once again like yesterday morning, gusty Santa Lucia (northeasterly) winds produced hot temperatures in the coastal valleys and along a few of the beaches. Cal Poly reported 96 degrees, while Diablo Canyon briefly reached 92 degrees at 5:30 a.m.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

SUN

MON

TUE

WED

THU

FRI

SAT

SUN

48, 85

52, 89

55, 91

56, 92

59, 92

59, 92

58, 90

55, 91

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUN

MON

TUE

WED

THU

FRI

SAT

SUN

54, 70

54, 76

55, 85

57, 78

56, 78

55, 79

56, 78

55, 78

John Lindsey is a longtime meteorologist who lives in Los Osos. Email him at JohnLindseyLosOsos@gmail.com.