SLO County heat wave simmers through coming week with more triple-digit highs

According to Dan Turner, director of Cal Poly’s Wildland-Urban Interface Fire Institute and a retired Cal Fire chief and business manager of the San Luis Obispo County Fire Safe Council, “Wind is the fire boss,” but it also plays the role of the “fog boss” in San Luis Obispo County’s coastal areas.

When the winds blow from the northwest toward the southeast, it’s likely that a marine layer with patches of mist and fog will form along the coastline, keeping the beaches pleasantly cool during the day.

If these northwesterly winds strengthen to strong to gale-force (25 to 38 mph) levels, they can mix out the temperature inversion layer, leading to sunny skies.

Conversely, coastal regions experience sunny and warmer weather when winds blow from the northeast. Understanding the influence of these winds is crucial in predicting and comprehending the local weather patterns.

For this upcoming week, strong to gale-force (25 to 38 mph) northwesterly winds will develop in the afternoon, clearing the skies along the beaches.

These oceanic winds we’ll keep the coastline and coastal valleys mild. However, the inland valleys will warm to near triple-digit levels on Sunday into Monday, cooling to the low-90s on Tuesday through Wednesday.

As high pressure builds overhead, inland temperatures will gradually warm on Thursday and Friday, reaching triple-digit levels on Saturday into next Sunday.

Strong to gale-force (25 to 38 mph) northwesterly winds will develop during the afternoon along the San Luis Obispo County coastline, decreasing during the night and morning starting on Sunday and continuing through Friday. These winds are expected to produce mainly clear skies during the late morning and afternoon hours, with fog and mist developing overnight in the coastal regions of San Luis Obispo County.

The coastal valleys (San Luis Obispo) will see highs in the mid-80s, while the inland areas (Paso Robles) will range between 100 and 103 degrees. Temperatures along the southerly facing beaches of Cayucos, Avila, and Shell Beach will warm in the high 70s, while Cambria, Morro Bay, Los Osos and Pismo Beach will reach the low-60s.

Much like last week, the models indicate variable amounts of subtropical moisture will stream northward over the Central Coast from Mexico. This condition will produce scattered mid- to high-level clouds, creating cooler temperatures but higher humidity levels on Monday into Wednesday.

A robust upper-level high-pressure system will develop over California starting Thursday and remain nearly stationary over the state through next Sunday. Consequently, temperatures will warm throughout the Central Coast, with the coastal valleys reaching the 80s and the inland valleys hitting triple-digit levels by next weekend.

Surf report

Strong to gale-force (25 to 38 mph) northwesterly winds will generate a 5- to 7-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 9-second period) along our coastline during the afternoon and night, decreasing to 4- to 6-feet during the morning on Sunday through Friday.

Combined with this northwesterly sea and swell will be 1- to 2-foot southern hemisphere (220-degree, deep-water) swell (with an 18- to 20-second period) on Wednesday.

Seawater temperatures will range between 56 and 58 degrees through Friday.

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.