Hey there, spring! SLO County weather forecast calls for warm, sunny week

San Luis Obispo County can expect a warm and sunny week — with lots of pollen in the air.

A strong ridge of high pressure over Central and Southern California will keep the storm track to the north of the Central Coast.

This week, the inland and coastal valleys will also experience the warmest temperatures of the year so far under mostly sunny skies.

A pattern of gentle to moderate (8 to 18 mph) Santa Lucia (northeasterly) winds developing during the night and morning, shifting out of the northwest and increasing to fresh to strong (19 to 31 mph) levels during the afternoon will continue through Monday.

This pattern will produce Chamber of Commerce weather with high temperatures reaching the mid-70s with good visibility.

However, at this time of year, when the wind shifts out of the northeast (offshore) and blows from the land to the ocean, they transport pollen from the grasses and trees in the inland valleys and mountains toward the sea.

At times like these, communities throughout the Central Coast will experience higher pollen counts.

A series of cold fronts will move through the Pacific Northwest, setting up steep pressure gradients along the Central California coastline.

In turn, strong to gale-force (25 to 38 mph with gusts to 45 mph) northwesterly winds will begin on Tuesday and continue through Saturday.

In fact, the northwesterly winds could reach moderate gale force to fresh gale force (32 to 46 mph) levels on Friday into Saturday.

These northwesterly winds will produce cooler seawater temperatures. As the winds blow parallel to our coastline, the friction causes ocean surface water to move.

Because of the Coriolis effect, the surface water flows to the right or offshore.

That, in turn, causes upwelling along the coast as cold, clear and nutrient-rich water rises from the ocean’s depths to the surface along the immediate shoreline to replace the shallow water that is pushed out to sea.

High temperatures in the inland (Paso Robles) and coastal valleys (San Luis Obispo) will reach the 80s on Tuesday through Thursday, and only the 60s along most of the coastline. The southerly-facing beaches of Cayucos, Avila Beach and Shell Beach, however, will reach the 80s.

The ridge of high pressure will weaken, allowing a cold front to produce rain throughout the Central Coast next Sunday and Monday.

Total rainfall should range between 0.10 and 0.33 of an inch. Snow levels will drop to 4,500 feet, and high air temperatures will struggle to reach the 60s.

At this time of the year, more potential instability develops in the atmosphere due to the longer days, which often produce thunderstorms with hail, gusty winds, and the threat of lightning strikes.

The long-range numerical models indicate an unsettled weather pattern with a chance of rain showers the following week.

Surf report

A 7- to 9-foot northwesterly (300-degree deep water) sea and swell (with a 7- to 17- second period) is forecast Sunday through Friday.

Combined with this northwesterly sea and swell will be a 2- to 3-foot Southern Hemisphere (210-degree deep water) swell (with a 16- to 18-second period) on Thursday through Friday.

Surface seawater temperatures will range between 51 and 53 degrees through Monday, decreasing to 49 and 51 degrees on Tuesday through Wednesday.

Seawater temperatures will further lower to 48 to 50 degrees on Thursday through Saturday.

On this date in weather history (April 6)

1989: Unseasonably hot weather prevailed in California. Afternoon highs of 91 degrees in downtown San Francisco, 93 degrees in San Jose, 98 degrees in San Diego, 103 degrees in Santa Maria, 104 degrees in Riverside and 106 degrees in downtown Los Angeles established records for the month of April.

2016: It was warm but not hot enough to break any daily records from the 1989 heatwave. Paso Robles reached 88 degrees, well below the daily record of 98 degrees set in 1989. Santa Maria hit 94 degrees, short of the 103 degree record from 1989. The San Luis Obispo County Regional Airport saw 97 degrees, nearly tying the record of 98 degrees from 1989. The 1989 heatwave event produced seven days of record-high temperatures from April 5 to 11 at the Paso Robles Municipal Airport.

2020: A storm produced nearly 4 inches of rain at Rocky Butte and 3.3 inches at Prefumo Canyon Crest Inn on top of the Irish Hills due to orographic enhancement.

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 X @PGE_John.