SLO County weather forecast for the week of July 24: Warm weather at the Mid-State Fair

A strong and persistent 1,037 millibar Eastern Pacific High, centered about 1,600 miles to the northwest of the Central Coast combined with a thermal low over the Central Valley will continue to produce a typical summer weather with night and morning marine low clouds with pockets of fog and mist in the coastal regions.

The afternoon northwesterly winds will decrease to gentle to moderate (8 to 18 mph) levels Sunday into Tuesday; consequently, the marine layer will be more persistent (No-Sky July) along the immediate coastline. The marine low clouds will spread inland during the night and morning with areas of fog and pockets of mist, clearing by the afternoon.

A 587-decameter upper-level low-pressure system over the Central Coast will produce mild summer temperatures. This week’s high temperatures will range from the low- to mid-70s in the coastal valleys (San Luis Obispo). The inland valleys (Paso Robles/Mid-State Fair) will range between the mid- to high-80s on Sunday into Wednesday, warming to the mid-90s on Thursday into Saturday, with no extreme heat events anticipated.

The afternoon northwesterly winds will increase to moderate to fresh (13 to 24 mph) levels on Wednesday into Saturday, creating a slight amount of clearing along the beaches during the afternoon.

For the first week of August, the long-range numerical models are advertising the return of monsoonal moisture to the Central Coast with higher relative humidity levels and virga — visible streaks of rain that fall from a cloud but evaporate before reaching the ground. This condition may also bring rain and thunderstorms to the Tehachapi and Sierra Nevada Mountains.

This day in weather history, July 24

1942 - The temperature at Las Vegas, Nevada, hit 117 degrees to set an all-time record for that location. The record was tied on July 19, 2005.

1952 - The temperature at Louisville, GA, soared to 112 degrees to establish a state record.

Surf report

A 4- to 6-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) will develop on Sunday, decreasing to 3- to 5-feet with the same period on Monday. This swell will further lower to 2- to 4-feet on Tuesday.

Moderate to fresh (13 to 24 mph) afternoon northwesterly winds will generate a 3- to 5-foot northwesterly (300-degree, deep-water) sea and swell (with a 5- to 8-second period) on Wednesday through next Saturday.

A 1- to 2-foot Southern Hemisphere (210-degree, deep-water) swell (with a 15- to 17-second period) will arrive on Tuesday and will remain at this level through Friday.

Seawater temperatures will range between 54 to 57 degrees through Friday.

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.