Weather Watch

What time of day do local temperatures peak? It depends

Special to The TribuneJune 8, 2013 

Sunset at the sand spit looking westward from Los Osos.

JOHN LINDSEY

Jill Cole from Paso Robles asked, “About what time of day do we usually have our highest temperatures in different parts of the Central Coast? Is the warmest hour of the day different during summer or winter?”

As the sun rises, the solar radiation increases until the sun is at its highest point in the sky at noon Pacific Standard Time or 1 p.m. daylight saving time. This is called solar noon. Even though the sun’s radiation is at its strongest then, that doesn’t necessarily mean that the maximum temperature will occur at that time.

You see, many inland areas of San Luis Obispo County will continue to climb so long as the earth is receiving more incoming heat than what is radiating back to space. On average, the summertime temperature will actually peak at 3:30 p.m. in Paso Robles. Further inland, Bakersfield doesn’t peak until 5 p.m. during the summer months. The delay between maximum solar radiation and the warmest time of the day is called thermal response. In fact, by the time the surface temperature reaches its maximum in the San Joaquin Valley, the amount of solar radiation reaching the surface has decreased almost by half of that at solar noon.

However, it’s a different story along our rugged coastline. We live in an area of many microclimates. The northeasterly Santa Lucia (offshore) winds and northwesterly (onshore) winds often clash with each other for supremacy.

This back-and-forth battle can produce hot temperatures in the late morning and then cool temperatures in the afternoon. That’s why a lot of us keep a sweater handy.

For example, San Luis Obispo will typically reach its highest daily summer temperature at 2 p.m. before the northwesterly (onshore) winds kick in to drive the temperature down.

On average, Los Osos reaches its maximum temperature at 11 a.m., while the Diablo Canyon Power Plant’s meteorological tower’s peak temperatures usually occur at 11:30 a.m. with the morning’s Santa Lucia winds.

During the winter months, the coastal areas reach their maximum temperature later in the day, while the inland areas hit their highs earlier.

A similar pattern occurs on a seasonal level. The sun’s radiation is at its greatest for the entire year at the summer solstice — the longest day of the year. Our atmosphere is a lot like a large freight train; it takes a lot of energy to get it going. This year’s summer will start June 20. However, the warmest months in San Luis Obispo County will not occur until August through September.

Awarding bright minds

The winners of the 2013 PG&E Bright Minds Scholarship were selected last week.

Emma Phillips, a senior at San Luis Obispo High School, was intrigued when Principal Leslie O’Connor summoned her and her father, Peter Phillips, who teaches at the school, to his office. Upon their arrival, San Luis Coastal Unified School District Superintendent Eric Prater and PG&E Government Relations Representative Eric Daniels announced that she had been awarded the scholarship, worth $30,000 a year and renewable for four additional years. To read more, visit www.pgecurrents.com.

Emma, who serves on the United Way Youth Board, plans to attend Brown University and aspires to be a neurologist.

John Lindsey’s column is special to The Tribune. He is a media relations representative for PG&E and a longtime local meteorologist. If you have a question, send him an email at pgeweather@pge.com.

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