SLO County weather forecast calls for a warm weekend. Will the sunshine last?

Warm conditions are expected through Monday, before cooler temperatures arrive on Tuesday through Thursday under partly cloudy skies. Then, another round of brisk, northwesterly winds and warmer temperatures are expected to develop later Friday and continue into the following week.

A moderately strong, 1,027-millibar, high-pressure system in the Eastern Pacific, located about 1,200 miles west of California, along with a ridge of high-pressure building from the southwest, will generate fresh-to-strong (19 to 31 mph) northwesterly winds this weekend.

This synoptic condition will also bring warm temperatures, with daytime highs reaching the low to mid-90s in the inland valleys, including Paso Robles, and the low 80s in coastal valleys such as San Luis Obispo.

Along the beaches, temperatures will generally range from the low to mid-60s. However, south-facing beaches such as Cayucos, Avila Beach and Shell Beach will see highs climb into the mid-70s this weekend.

The warm conditions will continue in inland areas on Monday, but much cooler temperatures and areas of low marine clouds and fog will develop along the southerly facing beaches as the winds relax and shift out of the west.

From Tuesday through Friday morning, the Eastern Pacific High will weaken and drift southward as an upper-level, low-pressure system (542 decameters) approaches California from the west.

As a result, winds will decrease and shift out the southwest, allowing low marine clouds with pockets of fog and mist to develop along the coastline and bringing cooler weather throughout San Luis Obispo and northern Santa Barbara counties under partly cloudy skies.

During this cooler period, daytime highs will only reach the upper 70s in the inland valleys and the low 70s in the coastal valleys. At all the beaches, temperatures will range from the upper 50s to the lower 60s.

On Friday through next Sunday, strong to gale-force (25 to 38 mph) northwesterly winds are forecasted. These winds will create mostly clear skies and warmer temperatures away from the coastline. In fact, the following week is also expected to remain quite windy.

Looking further ahead, many long-range climate models continue to indicate the potential development of a very strong El Niño event this winter. Some ensemble guidance even suggests the possibility of a record-strength event, which could lead to stormy conditions with above-average precipitation across California.

Surf report

A 6- to 8-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 15-second period) is expected this Saturday through Sunday.

Gentle to moderate (8 to 18 mph) southwesterly winds along the California coastline will allow a 4- to 6-foot northwesterly (290-degree, deep water) swell (with an 8- to 12-second period) to develop Monday, decreasing to 3- to 5-feet with the same period) on Tuesday into Friday morning.

Increasing northwesterly winds will generate a 5- to 7-foot northwesterly (310-degree, deep water) sea and swell (with a 5- to 11-second period) on Friday afternoon, increasing to 7 to 9 feet (with a 5- to 15-second period) on Saturday through next Sunday.

Arriving from the Southern Hemisphere, a 2- to 3-foot Southern Hemisphere (205-degree, deep water) swell (with a 16- to 18-second period) is forecast on Monday through Friday.

Seawater temperatures are expected to range from 51 to 53 degrees through Monday, increasing to 54 to 57 degrees from Tuesday into Friday. By the following weekend, temperatures will drop to between 50 and 54 degrees.

On this date in weather history (May 10)

1987: Summerlike, Father’s Day-type weather prevailed in the north central and western U.S. for Mother’s Day, as 17 cities reported record-high temperatures for the date. Jamestown, North Dakota, soared to a record high of 96 degrees. Thunderstorms along the Central Gulf Coast deluged Lillian, Alabama, with 14.5 inches of rain, and nearby Perdido Key, Florida, with 12.8 inches of rain. (Storm Data)

1989: Thunderstorms developing ahead of a cold front crossing the Plateau Region produced wind gusts up to 75 mph at Butte, Montana, and gusts up to 77 mph at Choteau, Montana. (Storm Data)

1990: A spring storm produced heavy snow in Upper Michigan and eastern Wisconsin. Totals ranged up to 12 inches at Marquette, Michigan, with 8 inches reported at Muskego, Wisconsin, and Hartford, Wisconsin. The heavy wet snow and winds gusting to 35 mph damaged or destroyed thousands of trees and downed numerous power lines. Total damage from the storm was more than $4 million. (Storm Data)

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

SUNDAY: 53, 93

MONDAY: 53, 94

TUESDAY: 52, 79

WEDNESDAY: 49, 77

THURSDAY: 48, 79

FRIDAY: 50, 82

SATURDAY: 51, 84

SUNDAY: 51, 83

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUNDAY: 56, 80

MONDAY: 55,82

TUESDAY: 56, 72

WEDNESDAY: 54, 71

THURSDAY: 53, 73

FRIDAY: 51, 71

SATURDAY: 50, 72

SUNDAY: 52, 73

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