“The coldest winter I ever spent was a summer in San Francisco.”

Alright, so Mark Twain may never have actually said it himself. But the statement still stands.

As any naïve tourist shivering miserably in a tank top and Bermuda shorts might attest, summertime in San Francisco can be downright frigid.

Welcome to the infamous “June Gloom.”

Even on days when the temperature in nearby cities climbs into the luscious 90’s (°F), it’s not uncommon to find much of San Francisco shrouded in a thick blanket of bone-chilling fog.

If you’re still a bit foggy (sorry, couldn’t resist) about why that is, scroll through this great interactive explainer created by Newsbound.

For a bit more clarity (about the fog, that is), watch the beautiful time-lapse film (at top) by Simon Christen, and below, this short video by KQED’s Quest that digs deeper into the science of coastal fog.

The Chilling Effect: Why San Francisco Gets So Dang Foggy in the Summer [Interactive] 20 June,2017Matthew Green

  • Karl the Fog

    Great post about my cardiovascular system. I focus so much on my emotions, it’s good to hear how I actually work.

    • Cecilia Hinojosa-Einhorn

      The cutest post!

  • Hunter Cutting

    Great that you posted these beautiful videos!

    But please get the science right. Fog is not “pulled in” by heat in the Central Valley. It is pushed in by high pressure off the coast, pushed into the low pressure zone created by air rising due to heat in the Central Valley. A nuance, to be sure, but an importance difference, and getting it wrong clouds thinking about the basic physics of the way weather works (pun intended). Please get it right.


      If there’s a pressure differential between the two places, how could there possibly be a “push” from one direction without a corresponding “pull” from the other?

  • bsman

    Only someone who lives in SF, Half Moon Bay or Pacifica would use the words “the glorious 90s”. We who have to live in these areas tend to find temperatures in the 90s rather less than glorious…

    • Mary Beth

      No sane person would use the words “glorious 90s.”

  • Kirk L Ives

    With the drought upon us we need fog everyday. It drops dew onto our trees, plants, and other greeneries to help them stay green and withstand the drought and also brings us fresh oxygen. I love the fog even more than the rain and the wind.

  • IkeSmith

    What fog?

  • Mary Beth

    Thank you, I was at first offended by the use of drawings but they did help.


Matthew Green

Matthew Green produces and edits The Lowdown, KQED’s multimedia news education blog, an online resource for educators and the general public. He previously taught journalism at Fremont High School in East Oakland, and has written for numerous local publications, including the Oakland Tribune and San Francisco Chronicle. Email: mgreen@kqed.org; Twitter: @MGreenKQED

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