A break from the heat: Clear skies and cooler temperatures forecast for SLO County

Last week, the weather pattern resembled summer rather than fall, with the Paso Robles Municipal Airport seeing six consecutive days of daily high-temperature records.

This string of record-high, triple-digit temperatures in the inland valleys was unprecedented for October, while gentle northwesterly (onshore) winds and the marine layer they brought kept the beaches mostly overcast and cool.

This week, a series of storms will move into the Pacific Northwest with rain and gale-force winds. Along the Central Coast, these low-pressure systems will push dry cold fronts through our region, creating steep pressure gradients along the California coastline.

These gradients will produce increasing northwesterly winds, cooler temperatures and clearer skies.

Starting on Sunday, a pattern of gentle to moderate (8 to 18 mph) Santa Lucia (northeasterly) winds will develop during the morning, shifting out of the northwest and increasing to fresh to strong (19 to 31 mph) levels during the afternoon. These winds will continue through Tuesday.

This pattern will produce cooler conditions and mostly clear skies, except for marine low clouds during the late evening and night and occasionally mid- to high-level clouds.

The inland valleys (Paso Robles) will reach the mid-80s, while the coastal valleys (San Luis Obispo) will hit the mid-70s. The beaches will range between the high 60s and low 70s, except for Cayucos, Avila Beach and Shell Beach, which will reach the mid-70s.

Strong to gale-force (25 to 38 mph with gusts to 45 mph) northwesterly winds are expected along the coastline on Wednesday through Saturday. These winds will bring a much cooler marine air mass to the entire region, with the inland and coastal valleys only reaching the 70s, while the beaches will mostly be in the 60s.

Next Saturday and Sunday, moderate to fresh (13 to 24 mph with gusts to 35 mph) Santa Lucia (northeasterly) winds will develop, producing clear skies and low relative humidity levels.

While the inland valleys will reach the high 60s over this time frame, the coastal valleys and beaches could see temperatures in the low 80s.

The long-range models do not indicate any significant rain as the storm remains far north of the Central Coast.

Surf report

A 6- to 8-foot northwesterly (295-degree deep water) sea and swell (with a 5- to 12-second period) is forecast along our coastline through Wednesday morning, building to 8- to 10-feet (with a 7- to 14-second period) on Wednesday afternoon through Friday.

A 4- to 6-foot northwesterly (300-degree deep water) sea and swell (with a 5- to 13-second period) is forecast next Saturday and Sunday.

A very long period (high energy) northwesterly swell is expected next week.

Combined with this northwesterly swell will be a 1- to 3-foot southern hemisphere (205-degree deep water) swell (with a 15- to 17-second period) on Sunday through Tuesday.

Surface seawater temperatures will range between 61 and 63 degrees through Tuesday. Increasing amounts of upwelling will decrease seawater temperatures to 53 to 57 degrees on Wednesday into next Saturday.

On this date in weather history (October 13)

1846: A great hurricane tracked across Cuba, Florida, Georgia, North and South Carolina, Virginia and Pennsylvania. The hurricane inflicted major damage along its entire path, which was similar to the path of Hurricane Hazel 108 years later. The hurricane caused great damage at Key West in Florida. In Philadelphia, it was the most destructive storm in thirty years. (David Ludlum)

2009: One of the most intense weather systems I’ve seen during the month of October produced stormy weather throughout the Central Coast. A 966-millibar low pressure system off the Oregon coastline and associated cold front produced heavy rain and fresh gale to strong gale (39 to 54 mph) southerly winds along our coastline and moderate gale to fresh gale (32 to 46 mph) winds in the coastal valleys.

24-hour rainfall totals:

• Diablo Canyon Ocean Lab, 2.48 inches
• SLOweather.com, 7.55 inches
• Vista del Lago in San Luis Obispo, 6.88 inches
• Cottontail Creek in Cayucos, 5.55 inches
• Lake Lopez, 4.13 inches
• Highway 41 between Morro Bay and Atascadero, 9.25 inches
• Highway 41 at Toro Creek “Paul’s House,” 7.8 inches
• Cambria Fire Department, 3.66 inches
• Paso Robles Municipal Airport, 1.85 inches

2020: Morning gusty Santa Lucia (northeasterly) winds coming down the Santa Lucia mountains produced some interesting temperatures. At 5:53 a.m., the Paso Robles Municipal Airport reported 49 degrees, while Cal Poly was at 85 degrees.

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.

This story was originally published October 13, 2024 at 5:00 AM.