SLO County weather: Mild but windy summer days ahead this week

A shift in the state’s weather pattern is on the way.

A series of cold fronts tracking from the Gulf of Alaska into the Pacific Northwest will bring rain showers as far south as Northern California and snow in the higher elevations in the northern and central Sierra Nevada.

The Central Coast, however, will remain dry.

What these systems will bring is wind.

Strong pressure gradients will develop along the California coast, producing steady afternoon northwesterly winds that will frequently reach strong to gale force (25 to 38 mph) through the week and into the weekend.

These winds will help rebuild the marine layer, leading to night and morning clouds with patches of fog, mist and drizzle. Conditions should clear by late morning or early afternoon.

Temperatures will cool to below seasonal norms for early September:

• Inland Valleys: (Paso Robles): Highs in the low to upper 80s.
• Coastal Valleys: (San Luis Obispo): Highs in the low to mid-70s.
• Beaches: Highs in the mid- to upper 60s, with south-facing beaches (Cayucos, Avila, Shell Beach) warming into the 70s.

Looking further ahead, forecasts point to a return of slightly above normal temperatures with continued dry conditions as September progresses.

Surf report

Gale-force northwesterly winds along the coastline will generate a 3- to 5-foot northwesterly (300-degree, deep water) sea and swell (with a 5-to 8-second period) through Monday morning, increasing to 5 to 7 feet (with a 5- to 12-second period) on Monday afternoon through next Sunday.

A 1- to 2-foot southern hemisphere (220-degree, deep water) swell (with a 14- to 16-second period) will arrive along our coastline on Wednesday and remain at this level through Thursday, fading away on Friday.

Surface seawater temperatures will range between 56 and 58 degrees through Monday, decreasing to 54 and 57 degrees on Tuesday and remain at this level through next Sunday.

On this date in weather history (Sept. 6)

1881: Forest fires in Michigan and Ontario resulted in “Yellow Day” in the northeastern United States. Twenty villages in Michigan burned, and a total of 500 people were killed. Fires caused 2.3 million dollars in losses near Lake Huron. Candles were needed at noon. (David Ludlum)

1929: Iowa’s earliest snow of record occurred as a few flakes were noted at 9 a.m. in Alton.

1989: An early afternoon thunderstorm produced wind gusts up to 104 mph at Winterhaven, Florida, flipping over four airplanes and damaging five others. The high winds also damaged a hangar and three other buildings. A cold front produced strong winds, blowing dust in the Northern High Plains, with gusts to 54 mph reported at Buffalo, South Dakota. (Storm Data)

2020: A powerful upper-level high combined with gusty Santa Lucia (northeasterly) winds produced unprecedented heat across the Central Coast. On that Sunday, the temperature at Cal Poly soared to an astonishing 120 degrees, while both San Luis Obispo and Paso Robles airports reached 117 degrees, shattering the all-time record of 115 degrees set on Sept. 2, 2017.

Santa Ynez Airport also reported 117 degrees, and Bulletin recorded 121 degrees. Even Santa Maria Airport, typically milder, hit 103 degrees, breaking its daily record of 96 degrees set in 1995.

The event was marked by dramatic overnight warming. Katabatic Santa Lucia winds cascaded down the Cuesta Grade, enhanced by the dry adiabatic lapse rate, which drove rapid temperature spikes. At Cal Poly, the temperature rose from 76 degrees at 2:54 a.m. to 103 degrees just one hour later. By 4:30 a.m., stations across the Central Coast showed extreme contrasts: the Diablo Canyon nuclear power plant registered a cool 58 degrees, while nearby Davis Peak measured 94 degrees.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

SUNDAY: 53, 87

MONDAY: 54, 84

TUESDAY: 54, 84

WEDNESDAY: 52, 82

THURSDAY: 52, 81

FRIDAY: 51, 80

SATURDAY: 53, 87

SUNDAY: 54, n/a

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUNDAY: 55, 74

MONDAY: 56, 72

TUESDAY: 56, 75

WEDNESDAY: 54, 73

THURSDAY: 54, 71

FRIDAY: 53, 70

SATURDAY: 55, 71

SUNDAY: 55, 74

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

This story was originally published September 7, 2025 at 5:00 AM.