Foggy skies for coastal SLO County this week as heat lingers inland

The normal temperature during July at Paso Robles Municipal Airport stands at 73.4 degrees. However, the airport recorded an average temperature of 77.2 degrees last month, indicating a deviation of 3.8 degrees, making it hotter than typical. Conversely, San Luis Obispo County Regional Airport experienced an average temperature of 67.7 degrees in July, approximately 1.5 degrees higher than the historical data.

Across most coastal areas, temperatures have trended cooler than usual due to the consistent marine layer presence. This has led to overcast skies with intermittent mist and fog. This week, a comparable weather pattern is anticipated along the coastal regions. Marine low clouds will prevail, accompanied by pockets of mist and light drizzle overnight. In fact, a significant portion of the beaches might remain overcast throughout the day, often referred to as “Fogust.”

The prevailing winds are expected to be gentle to moderate, ranging from 8 to 18 mph, blowing in from the northwest until Saturday.

Moving away from the coastline, the inland valleys, such as Paso Robles, will experience triple-digit temperatures. In contrast, the coastal valleys, like San Luis Obispo, will reach the mid-80s.

A tropical cyclone is expected to develop off Baja California on Sunday. Variable amounts of subtropical moisture will stream northward over the Central Coast from this storm. This condition will produce scattered mid to high-level clouds, creating cooler temperatures but higher humidity levels on Monday into Tuesday with the inland valleys warming to the mid-90s and the coastal valleys reaching the 70s.

North County temperatures will warm to the low-100s by Thursday and will continue to reach triple-digit levels through the following week. The coastal valleys will reach the 80s by Friday and are expected to warm to the 80s through the following week. The beaches should remain overcast and cool.

The weather models still do not indicate any Santa Lucia (northeasterly) wind events as a thermal low remains over the Central Valley and the Eastern Pacific is anchored west of San Luis Obispo County.

Surf report

A 5- to 7-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) is expected along our coastline on Sunday, decreasing to 4- to 6-feet by Monday. This swell will decrease to 3- to 5-feet with the same period on Tuesday and will remain at this level through Saturday.

Combined with this northwesterly sea and swell will be 1-foot southerly (180-degree, deep-water) swell (with an 11- to 14-second period) on Monday through Wednesday.

Seawater temperatures will range between 55 and 57 degrees through Tuesday, increasing to 56 to 58 degrees on Wednesday through Saturday.

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.