Rain, then heat, then rain again? SLO County is in for some erratic weather this week

An early-season low-pressure system and associated cold front was expected to move through the Central Coast on Saturday into Sunday morning with patchy drizzle, widely scattered rain showers and cooler temperatures. Rainfall amounts are expected to remain below 0.10 of an inch, with snow levels at 7,000 feet.

Partly cloudy and fresh to strong (19 to 31 mph) northwesterly winds will develop Sunday afternoon, with the marine layer redeveloping and deepening Sunday night into Monday morning with pockets of fog and mist.

High temperatures on Sunday through Monday will only reach the high 60s to low 70s in the inland valleys (Paso Robles) and coastal valleys (San Luis Obispo). The beaches will remain in the 60s.

Warmer temperatures and decreasing winds will develop on Tuesday through Friday as a ridge of high pressure strengthens over the Central Coast. High temperatures on Tuesday through Friday will reach the high 80s to the low 90s in the inland valleys and the low to mid-80s in the coastal valleys. The beaches will warm up to the 70s. Marine stratus clouds with areas of fog and mist will continue to develop overnight, clearing during the late morning and afternoon.

Another trough of low pressure is expected to develop along the California coastline next Saturday through next Monday with cooler conditions, increasing clouds, and the chance of scattered rain showers.

The long-range models indicate possibly more rain by mid-October. There are still no signs of and significant Santa Lucia (northeasterly) wind events.

Surf report

A 5- to 7-foot northwesterly (295-degree, deep-water) swell (with an 8- to 11-second period) is expected along our coastline on Sunday.

A powerful Gulf of Alaska storm on Saturday will generate longer wavelengths. This long-period northwesterly (290-degree, deep-water) swell (with an 18- to 20-second period) will arrive along the Central Coast later Monday, remaining at a 4- to 6-foot level, but with a 15- to 17-second period) on Tuesday through Wednesday.

A 3- to 5-foot northwesterly (295-degree, deep-water) swell (with an 8- to 12-second period) is expected along our coastline Thursday into Friday.

Seawater temperatures will range between 55 and 57 degrees through Monday, increasing to 56 to 58 degrees on Tuesday through Wednesday, further warming to 60 to 63 degrees Thursday through next Sunday.

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.

This story was originally published October 1, 2023 at 5:00 AM.