Fogust: San Francisco shivers through coldest August days in 74 years

Photo: Liz Hafalia, The Chronicle Fog seen over San Francisco from north side of the bridge on...

The last time San Francisco shivered under an August that stayed so cold was 1942. Franklin D. Roosevelt was president, Japanese Americans were being sent to internment camps, America fought the Battle of Guadalcanal, and Casablanca wasn't even released yet.

This August it never rose above 70 degrees in Downtown San Francisco, and the last time that can be said was 74 years ago.

The full monthly numbers are in and the average high temperature for the month was only 65 degrees exactly, which made August's high temperatures colder than February's.

It was also colder even than July, which averaged 65.2 for the high, and much colder then February, when the average high temperature was a balmy 66.4 degrees.

Looking at averages, we've had plenty of cold Augusts.

August of 2006 was actually a little cooler than this year, with an average daily high of 64.6, but that month, it still had a day where the thermometer struck 71.1 degrees.

In 1949, the average daily high was 64.8, but the mercury still managed one day to get up to 71.1. Not so this year.

By comparison, last February's mercury rose clear up to 77 degrees one day.

It almost warmed up this past week, as a hurricane out in the Pacific briefly shifted our weather pattern, and created GORGEOUS sunsets, as seen in the photo gallery. But it quickly bounced back to cool and drizzly mornings and evenings.

A beautiful sunset graced the skies above the Bay Area on August 29th, 2016. A beautiful sunset graced the skies above the Bay Area on August 29th, 2016. Photo: Courtesy Rob Cotton Photo: Courtesy Rob Cotton Image 1 of / 40 Caption Close Fogust: San Francisco shivers through coldest August days in 74 years 1 / 40 Back to Gallery

Jan Null with Golden Gate Weather Services explains the deeper the marine layer, the more fog gets pulled in, and the stronger the afternoon ocean breeze is blowing into the Central Valley. We had a deep marine layer this summer, and that kept a strong, cool ocean breeze, or our "natural air conditioner."

Interestingly, looking at the entire summer, San Jose has been right on average, while in the Central Valley, cities were up to 2.5 degrees above normal daily high temperatures this summer.

IMAGE FROM GGWEATHER.COM:

These numbers look at the maximum high temperatures. February did have lower low temperatures, so the overall monthly average temperatures in winter were cooler. It's just the daily highs that are so interesting, and so important for that backyard barbecues, jogs along the Embarcdero, or bundled up walks upwind to the MUNI station.

Don't worry. Warm October is coming, as September and October are our hottest months of the year in the City by the Bay.