Weather Watch

Heat in SLO County has been record-breaking — here’s what it means for the rainy season

The sun sets over the Pacific Ocean on a hot summer night.
The sun sets over the Pacific Ocean on a hot summer night. Special to The Tribune

Back in June, I assumed after three straight years of record-breaking high air temperatures in Central California that this year would be cooler than normal due to the neutral condition — the infamous “El Nothing” or “El Nada” currently present in the central equatorial region of the Pacific Ocean.

The neutral condition combined with near- or below-average seawater temperatures along the California coastline caused by stronger than typical springtime northwesterly winds led me on the wrong path to my hypothesis.

The U.S. Climate Prediction Center called for “above-normal temperatures” for the Central Coast for June, July and August. Well, their forecast verified.

Santa Maria Airport’s averaged temperature was 64.1 degrees over this period. Typically, the average temperature at the airport is 62.4. San Luis Obispo Municipal Airport checked in at 67.8 degrees or 2.6 degrees warmer than normal for June, July and August. Away from the coast, Paso Robles Airport averaged 75.5 degrees. The usual temperature over this period is 71.9 degrees. By the way, that North County location recorded 30 days of temperatures exceeding 100 degrees.

In fact, August saw five daily high-temperature records broken.

If you’re fond of above-average temperatures, you’re in luck; the U.S. Climate Prediction Center is calling for above-average temperatures for the Central Coast and the rest of the United States for September, October and November.

How will above-average temperatures affect rainfall? Carie Sindt sent an email asking this question.

The neutral condition is forecast to continue through winter. Neutral conditions typically don’t produce any reliable seasonal rainfall predictions along the Central Coast.

However, another great oceanographic cycle that can orchestrate changes in our weather is a longer lasting cycle called the Pacific Decadal Oscillation or PDO. While the ENSO phase typically lasts from eight to 13 months, the PDO alternates between a warm phase (positive) and a cooler (negative) phase that can last a few years to decades. Unlike El Niño, which focuses on SST in the central equatorial region of the Pacific Ocean, the PDO is classified by seawater temperatures throughout the northern Pacific Ocean.

According to climatologist Bill Patzert of NASA’s Jet Propulsion Laboratory in Pasadena, the PDO shifted to the positive in 2014. Historically, the positive phase of the PDO typically enhances the effects of El Niño and La Niña events. Historically along the Central Coast, El Nothing combined with a positive PDO has produced near average amounts of rainfall.

I think we will receive near normal amounts of precipitation this rain season, which started July 1 and continues through June 30, 2018. However, a warmer atmosphere can hold more water vapor, meaning we could see more intense rainfall events this season.

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John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at or follow him on Twitter @PGE_John.

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