SLO County weather forecast for the week of June 20: Cooler temperatures and winds

Last week saw clear skies and record-breaking temperatures. San Luis Obispo County Airport hit 109 degrees on Wednesday, smashing the previous daily record high of 101 degrees in 1981; the following day, the Paso Robles Airport hit 109 degrees, breaking the previous daily record high of 104 recorded in 2017.

Night and morning marine low clouds with areas of fog and mist will develop on Sunday, becoming clear during the afternoon. High temperatures on Sunday will range from the mid-90s in the inland valleys (Paso Robles) and mid-70s in the coastal valleys (San Luis Obispo). The beaches will remain in the 60s with partial afternoon clearing.

The high-pressure ridge responsible for the hot weather will weaken and shift eastward on Monday into Tuesday. At the same time, a trough of low pressure is forecast to develop along the California coast.

A deep marine layer (June Gloom) will develop on Monday (the first full day of summer) through Wednesday morning, which is expected to produce night and morning drizzle, at times heavy, along the coastline.

This marine influence will bring cooler temperatures to the entire Central Coast, with the inland valleys only reaching the high 70s while the coastal valleys the high 60s. The beaches will range between the high 50s to the low 60s under overcast skies throughout the day.

Increasing northwesterly winds on Wednesday afternoon through Friday will produce clearing skies during the afternoon along the beaches and warmer temperatures throughout the Central Coast as high pressure builds over California.

Temperatures will continue to rise away from the coastline this upcoming weekend, but the beaches will be overcast and cool as gentle to moderate (8 to 18 mph) northwesterly winds develop.

Surf report

Sunday’s 4- to 6-foot northwesterly (295-degree, deep-water) swell (with an 8- to 11-second period) will lower to 3 to 5 feet (with an 8- to 12-second period) on Monday through Wednesday morning.

Increasing northwesterly winds along the California coastline will generate a 4- to 6-foot northwesterly (305-degree, deep- water) sea and swell (with a 5- to 11-second period) on Wednesday afternoon through Friday.

Arriving from the Southern Hemisphere is 1- to 2-foot Southern Hemisphere (195-degree, deep-water) swell (with a 16- to 21-second period) is forecast to arrive along our coastline on Sunday, increasing to 3 to 4 feet (with a 15- to 18-second period) on Monday through Wednesday.

Seawater temperatures will range between 54- and 57-degrees through Saturday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

This week’s long-period Southern Hemisphere swell will produce rip currents, and sneaker waves and present possibly dangerous conditions along the beaches. Remember, never turn your back on the ocean.

John Lindsey’s is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.