No break yet from heat wave. Here’s what’s ahead in the SLO County forecast

Last week, the Paso Robles Municipal Airport set a new daily high-temperature record for three consecutive days.

The inland valleys (Paso Robles) are expected to continue to hit triple-digit temperatures this week while the coastal valleys (San Luis Obispo) will be in the 90s through Sunday. However, the heat will not likely surpass daily records this week — and here is why.

In early October 1987, a strong high-pressure ridge and Santa Lucia (northeasterly) winds triggered an intense heatwave across California. San Luis Obispo was the hottest spot in the nation, recording 111 degrees at the airport two days in a row.

The Santa Maria Public Airport reached 108 degrees on Oct. 4, 1987, while Lompoc hit 110 degrees. Due to the warm overnight temperatures, many Cal Poly dorms became giant brick ovens, forcing students — including me — to sleep outside.

This week, however, an upper-level high-pressure system centered over Southern California will continue to produce a gentle breeze and blow hot temperatures away from the immediate coastline through Monday.

The inland valleys (Paso Robles) will reach triple-digit levels, while the coastal valleys (San Luis Obispo) will hit the 90s. The beaches will remain mild, only reaching the 60s under mostly overcast skies.

The upper-level high-pressure system responsible for the hot temperatures and gentle winds will move eastward and be replaced by an upper-level trough along the California coastline from Tuesday through next Saturday.

This condition will create fresh to strong (19 to 31 mph) northwesterly winds during the late morning and afternoon and cooler temperatures away from the ocean. This onshore flow will allow the marine layer to surge inland overnight with pockets of dense fog and mist.

The winds should be strong enough to mix out the temperature inversion layer, leaving behind sunny skies along the beaches.

Over this period, the inland valleys will range between the mid-80s and low 90s, with the coastal valleys (San Luis Obispo) reaching the high 70s to the low 80s.

The beaches will range between the low to mid-60s, except for Cayucos, Avila Beach and Shell Beach, which will reach the mid-70s.

Seawater temperatures have warmed to the low 60s over the last week, which will impact beach air temperatures.

The long-range models do not indicate any significant rain as the storm remains far north of the Central Coast.

Surf report

A 2- to 4-foot northwesterly (290-degree deep water) swell (with an 8- to 11-second period) is forecast along our coastline through Monday morning, increasing to 3- to 5-feet (with an 18- to 20-second period) on Monday afternoon.

This northwesterly swell will further build to 5- to 7-feet (with a 16- to 18-second period) by Monday night into Tuesday morning due to storm activity in the Gulf of Alaska.

Increasing northwesterly winds will generate a 6- to 8-foot northwesterly (305-degree deep water) sea and swell (with a 5- to 15-second period) along our coastline Tuesday afternoon through next Saturday.

Combined with this northwesterly swell will be a 1- to 3-foot southern hemisphere (220-degree deep water) swell (with a 13- to 15-second period) through Monday.

A 1- to 3-foot southern hemisphere (215-degree deep water) swell (with a 14- to 16-second period) will arrive along our coastline on Wednesday into next Saturday.

Surface seawater temperatures will range between 61 and 63 degrees through Tuesday, cooling to 58 to 61 degrees on Wednesday through Thursday.

The Pacific Ocean along the immediate Central Coast shoreline will further cool to 55 to 58 degrees on Friday into next Saturday.

On this date in weather history (Oct. 6)

The western United States continued to sizzle. Afternoon highs of 85 degrees in Astoria, Oregon; 101 degrees in Tucson, Arizona; and 102 degrees in Sacramento, equaled October records. It marked the fourth time in the month that Sacramento tied its record for October. The heat wave in San Luis Obispo ended.

An upper-level low pressure system produced almost uniform rainfall totals throughout the Central Coast:

Doppler radar from Vandenberg Space Force Base indicated rain showers, like boxcars in a train, moving parallel and off the shoreline towards Southern California. The beaches and coastal valleys of San Luis Obispo County remained dry that day.

This week's temperatures