SLO County weather forecast: Expect warm coastal temperatures with morning fog

A typical July weather pattern will continue through this upcoming week with night and morning marine low clouds with areas of fog and pockets of mist.

Strong to gale force (25 to 38 mph) afternoon northwesterly winds along the coastline on Sunday will produce mostly clear afternoons. This weekend’s high temperatures will range from the high-70s in the coastal valleys (San Luis Obispo) and the high-90s in the inland valleys (Paso Robles). The beaches will remain in the 60s, except the southerly facing beaches of Cayucos, Avila Beach and Shell Beach which will reach the 70s.

The northwesterly winds will decrease to gentle to moderate (8 to 18 mph) levels on Monday into Tuesday, increasing to moderate to fresh (13 to 24 mph) levels on Wednesday Consequently, the marine layer will be more persistent (No-Sky July) along the entire immediate coastline with cooler temperatures.

Away from the ocean, a large upper-level high over Texas will move westward toward the Four Corners area. This condition will keep the inland valleys in the mid to high-90s throughout this week. There is also a chance of some monsoon moisture reaching the Central Coast later in the week with increasing high-level clouds and higher relative humidity levels, but no rain.

Strong to gale force (25 to 38 mph) afternoon northwesterly winds along the coastline will start on Thursday and continue through Saturday. This condition will produce clear skies along the beaches during the afternoon.

Surf report

Sunday’s 4- to 6-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 8-second period) will remain at this level into Sunday night.

A 3- to 5-foot northwesterly (300-degree, deep-water) swell (with an 8- to 11-second period) will develop on Monday, decreasing to 2- to 4-feet with the same period on Tuesday into Wednesday.

Strong to gale force (25 to 38 mph) northwesterly winds along the Central Coast will generate a 4- to 6-foot northwesterly (305-degree, deep-water) sea and swell (with a 5- to 8-second period) on Thursday, increasing to 7- to 9-feet with the same period on Friday into Saturday.

A 1- to 2-foot Southern Hemisphere (220-degree, deep-water) swell (with a 16- to 18-second period) will arrive on Wednesday and will remain at this level through Friday.

Tropical Storm Bonnie, about 600 miles west of Baja California, is not expected to impact our area.

Seawater temperatures will range between 54 to 57 degrees through Wednesday, decreasing to 52 to 54 degrees on Thursday into Saturday.

This Date in Weather History

1913 - The mercury hit 134 degrees at Greenland Ranch in Death Valley, CA, the hottest reading of record for the North American continent. Sandstorm conditions accompanied the heat. The high the previous day was 129 degrees, following a morning low of 93 degrees. (David Ludlum)

2017 - Extensive monsoon moisture streaming from the southwest has mixed out the marine layer. Nonetheless, the marine influence will remain persistent today and will produce cooler temperatures throughout the Central Coast.

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.