SLO County could see a heat wave in August. Could it break local records?

This July has seen a “Chamber of Commerce” weather pattern with the coastline and coastal valleys (San Luis Obispo, Santa Maria, and Lompoc) running about 1 degree above typical, while the inland valleys (Paso Robles and Santa Ynez) have been about 1 degree below normal.

However, this near-perfect pattern may change by the middle of August. Some of the long-range models are advertising a large area of high pressure expanding from the Desert Southwest, creating well above average temperatures throughout the Central Coast. Historically in August and September, it almost seems inevitable that monsoonal moisture with higher humidity levels and a chance of thunderstorms will follow a warm spell.

If you’re a weather geek like me, you’ll probably find temperature records fascinating. I’ve put together some local all-time highs.

In the first week of October 1987, a robust and high-pressure ridge combined with Santa Lucia (northeasterly) winds produced a scorching heatwave across California. San Luis Obispo was the warmest location in the nation, with 111-degree temperatures recorded at the airport two days in a row. The Santa Maria Public Airport reached 108 on Oct. 4, while Lompoc hit 110, breaking that location’s all-time high.

Because of the warm overnight conditions, many of the Cal Poly dorms warmed up like large brick ovens and forced many students to sleep outside — including me.

A small (mesoscale) high-pressure system developed in the eastern portion of the Central Coast on the first day of summer on June 20, 2008, and combined with a warm, upper-atmosphere, high-pressure ridge over California, produced record-breaking temperatures along the beaches and coastal valleys.

As the longest day of the year emerged, the early morning Santa Lucia (northeasterly) winds caused the mercury to soar. The PG&E meteorological tower at Los Osos Valley Road and Foothill Boulevard in western San Luis Obispo reported 114. The Santa Maria Public Airport reached its all-time record high of 110, while the Lompoc Airport saw 109. Diablo Canyon hit its all-time high of 101, while the San Luis Obispo County Airport reported 111.

On that morning when I walked out the door of my home in Los Osos, an eerie cracking sound, like bacon frying in a pan could be heard throughout Baywood Park as the pinecones from Monterey pine trees opened in the 103-degree heat and their seeds rotated like small helicopters to the ground.

For decades, the official record-high temperature in San Luis Obispo was 112 recorded on Sept. 14, 1971, until a blistering week that fueled numerous wildfires around the state produced a 114-degree reading at the San Luis Obispo County Airport on Sept. 2, 2017. The temperature at the Paso Robles Airport climbed to 115, matching the all-time record high set on July 20, 1960. The Santa Maria Airport registered a high of 106 degrees, breaking the record for Sept. 2 of 95 degrees, established in 1955. Bonnie Wollam reported a high of 117.3 at Chumash Village Mobile Home Park in San Luis Obispo.

It was believed that the highest temperature ever recorded in the United States occurred at Furnace Creek in Death Valley on July 10, 1913, when the temperature reportedly hit 134 degrees. However, there are questions about the accuracy of the data.

A recent article by by Christopher C. Burt says: “It is possible to demonstrate that a temperature of 134°F in Death Valley on July 10, 1913, was essentially not possible from a meteorological perspective, using an officially sanctioned USWB shelter and thermometer and following proper procedures observationally. Thus, the best explanation for the record high report(s) in July 1913 is observer error.”

On July 12 of this year, Death Valley saw a high of 128 degrees. This was a degree short of the all-time hottest temperature ever recorded on Earth according to the World Meteorological Organization of 129 degrees, which occurred in Death Valley in 2013.

Another story persisted that Santa Barbara was believed to have reached 133 on June 17, 1859, because of compressive heating as gale-force (sundowner) winds sloped down the Santa Ynez Mountains.

A U.S. Coast Survey crew was reported to be at sea off the coast of Santa Barbara and supposedly recorded the 133 temperature. The fruit fell to the ground and birds dropped from the sky, according to personal accounts. That report has since been rebuked by numerous historians.

PG&E is hosting a series of online webinars for anyone interested in learning more about our Community Wildfire Safety Program. These virtual gatherings allow community members to learn more about wildfire safety and emergency preparedness, meet with PG&E representatives, ask questions, and share feedback. A webinar for San Luis Obispo and Santa Barbara counties, will be held on Wednesday, July 29, 5:30 to 7 p.m. Please visit www.pge.com or https://twitter.com/PGE_John for the webinar link.