SLO County weather forecast: Chance of rain this week, before a heat wave arrives
Chamber of Commerce weather will hold steady along the Central Coast through this week, with the potential for a mid-October heat wave developing the following week.
Fresh to strong (19-31 mph) afternoon northwesterly winds, paired with gentle to moderate (8-18 mph) Santa Lucia (northeasterly) winds at night and in the morning, will keep skies mostly clear through Sunday.
From Monday through Thursday morning, winds will ease, allowing low marine clouds to form along the coast and drift inland during the late night and morning hours.
Afternoon highs will reach the upper 70s to low 80s in the inland valleys (Paso Robles), while the coastal valleys (San Luis Obispo) warm into the mid-70s. Beaches will remain cooler, ranging from the mid- to upper 60s.
By Thursday afternoon, fresh to strong northwesterly winds will return and persist until Friday. These winds will help scour out the marine layer, but another surge of subtropical moisture is expected Friday. This system will bring mid- to high-level clouds and a chance of rain showers on Saturday and Sunday.
Looking further ahead, numerical weather models point toward a mid-October heat wave, with many coastal locations climbing into the 90s. Overall, dry conditions are expected to persist through the end of October.
Surf report
A 2- to 4-foot northwesterly (290-degree deep-water) swell (with an 8- to 14-second period) is forecast along our coastline Monday, decreasing to 2 to 3 feet on Tuesday through Thursday morning.
Increasing northwesterly winds will generate 3- to 5-foot northwesterly (305-degree deep-water) sea and swell (with a 5- to 11-second period) Thursday afternoon through Friday.
Seawater temperatures will range between 58 and 61 degrees through Monday, increasing to 59 to 62 degrees on Tuesday and will remain at this level through next Sunday.
On this date in weather history
1987: In the first week of October 1987, a robust high-pressure ridge combined with Santa Lucia (northeasterly) winds to produce a scorching heatwave across California. Afternoon highs of 102 degrees in downtown San Francisco and 104 degrees at Monterey established all-time records. The high of 101 degrees at San Jose was a record for October. San Luis Obispo was the warmest location in the nation, with 111-degree temperatures recorded at the airport two days in a row. The Santa Maria Public Airport reached 108 on Oct. 4, while Lompoc hit 110, breaking that location’s all-time high. Because of the warm overnight conditions, many of the Cal Poly dorms warmed up like large brick ovens and forced many students to sleep outside — including me.
1998: Wave data from the Diablo Canyon Waverider Buoy and the Huntington Beach Array indicated that a long-period swell from the south-southwest had peaked at 6.3 feet with a 20-second period.
2020: The high temperature at Diablo Canyon reached 97 degrees for about three hours between 4:30 and 7:30 p.m. Cal Poly hit 108 degrees, besting the old record of 105 recorded in 1980.
2021: An upper-level low over Southern California produced rain showers in Shell Beach, Avila Beach, Port San Luis, and Diablo Canyon. Santa Barbara County saw thunderstorms that produced lightning, hail and rain. In Northern Santa Barbara County, Santa Ynez reported 0.02 inches of an inch of rain, while Santa Maria and Lompoc saw trace amounts.
This week’s temperatures
LOWS AND HIGHS, PASO ROBLES
SUNDAY: 49, 80
MONDAY: 50, 78
TUESDAY: 50, 80
WEDNESDAY: 51, 81
THURSDAY: 52, 79
FRIDAY: 53, 81
SATURDAY: 54, 82
SUNDAY: 55, 80
LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS
SUNDAY: 52, 74
MONDAY: 52, 70
TUESDAY: 53, 71
WEDNESDAY: 53, 73
THURSDAY: 54, 71
FRIDAY: 53, 75
SATURDAY: 55, 78
SUNDAY: 54, 76
John Lindsey is a retired PG&E marine meteorologist. Email him at JohnLindseyLosOsos@gmail.com or follow him on X @PGE_John.