SLO County weather forecast: Expect mild temperatures throughout the week

Much like during the first half of October 2017, a trough of low pressure along the California coastline will produce moderate to fresh (13 to 24 mph) afternoon northwesterly (onshore) winds, decreasing during the overnight, plenty of low marine clouds with pockets of fog and drizzle during the night and morning. In the upper levels of the atmosphere, an Omega Block will keep the storm track to the north of California. Overall, temperatures will remain mild.

Persistent northwesterly (onshore) winds will allow the marine layer to move inland overnight with pockets of mist and drizzle, clearing from most areas during the late morning and afternoon. A few of the beaches may remain overcast throughout the day.

High temperatures on Sunday will range from the high-50s to low-60s at the beaches, the low to mid-70s in the coastal valleys (San Luis Obispo), and the mid-80s in the inland valleys (Paso Robles).

A slug of subtropical moisture is expected to produce rain showers and a chance of thunderstorms in the Sierra Nevada and Tehachapi mountains on Monday.

Slightly cooler temperatures are forecast on Tuesday into Wednesday, with the inland valleys reaching the low-80s. Overnight lows in the inland valleys will drop to the low- 40s.

Strong to gale-force (25 to 38 mph) northwesterly winds will develop during the afternoon on Wednesday into Saturday. These winds will mix out the temperature inversion layer producing clear skies during the afternoon along the coastline. Away from the ocean, a gradual warming trend is forecast on Thursday through Saturday, with the inland valleys hitting the mid to high-80s.

At this time, this weather pattern is expected to continue through next week, as there are still no signs of the Santa Lucia (northeasterly/offshore) winds.

Surf report

Saturday’s 3- to 5-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 12-second period) will remain at this level into Sunday, becoming a 2- to 4-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) on Monday through Wednesday morning.

Strong to gale-force (25 to 38 mph) northwesterly winds will generate a 5- to 7-foot (310-degree, deep-water) sea and swell (with a 5- to 8-second period) on Wednesday afternoon into next Saturday.

A 2- to 3-foot Southern Hemisphere (205-degree, deep-water) swell (with a 15- to 17-second period) is expected along our coastline on Monday through Tuesday.

Seawater temperatures will range between 55 and 58 degrees through Saturday.

This Date in Weather History (October 9):

1871 - (October 8 & 9): Prolonged drought and desiccating winds led to the great Chicago fire, the Peshtigo horror, and the Michigan fire holocaust. Fire destroyed more than 17,000 buildings, killing more than 200 people in the city of Chicago, while a fire consumed the town of Peshtigo, WI, killing more than 1,100 people. In Wisconsin, a million acres of land were burned, and in Michigan, 2.5 million acres were burned, killing 200 people. “Tornadoes of fire” are generated by intense heat caused houses to explode in fire. (David Ludlum)

1989 - Unseasonably warm weather continued in the western U.S. as the San Francisco Giants won the National League pennant. San Jose, CA reported a record high of 91 degrees.

2015 - San Luis Obispo reached 100 degrees, falling short of the previous record of 106 setback 1996. However, today’s high temperature is forecast to reach 99. If this temperature verifies, it will break the previous record of 98 recorded in 1994. This morning’s gusty Santa Lucia (northeasterly) winds produced mild temperatures along the coastline. At 4 a.m., the Diablo Canyon meteorological tower reported a temperature of 74 degrees, while the Point San Luis Lighthouse hit 70.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

John Lindsey is a longtime meteorologist who lives in Los Osos. Email him at JohnLindseyLosOsos@gmail.com.