Weather of the San Francisco Bay Region

California Natural History Guides #63

by Harold Gilliam, Bill Nelson (Illustrator)

Possibly no comparable area on earth displays as many varieties of weather simultaneously as the San Francisco Bay Region. Harold Gilliam explains the atmospheric forces and geologic formations that come together in this region's unique confluence of wind, river, ocean, bay, and hills. The fully revised and updated edition of this best-selling book incorporates the latest scientific information--much of it gathered from satellite technology--that has greatly improved our understanding of the weather in the years since the book was first published. Writing in a delightfully engaging style, Gilliam provides the tools necessary for understanding the grand show of nature that takes place around the San Francisco Bay--from Napa Valley in the north to San Jose in the south.

Using nontechnical language to define weather terms and the general principles needed to understand weather patterns, Gilliam explains such phenomena as the jet stream, the famous summer fog that pours over the Golden Gate Bridge, and the often dangerous winter tule fog. This edition also includes a discussion of the planetary influences that may cause long-term changes in the local Gilliam explains the "greenhouse effect" and what global warming could mean for the San Francisco Bay Area, looks at the local effects of the El Niño and La Niña phenomena, and considers the thinning of the ozone layer.

This fascinating book, enhanced with informative maps, diagrams, and color illustrations, is liberally sprinkled with references to Bay Area neighborhoods and geographic features, giving the book a lively sense of local color.

Genres: Science, Nonfiction, Nature, Reference

115 pages, Paperback

First published October 1, 1962

About the author

From Wikipedia:

Harold Gilliam is a San Francisco based writer, newspaperman and environmentalist, graduate of UC Berkeley, author of many books and former columnist for the San Francisco Chronicle and Examiner. The "Harold Gilliam Award for Excellence in Environmental Reporting", given by the Bay Institute of San Francisco, is named in his honor. Gilliam’s article, "The Destruction of Mono Lake Is on Schedule" appeared in the Examiner’s Sunday edition in March, 1979, and was one of the first articles to draw attention to Mono Lake’s plight.

Reviews

[Richard · Rating 5 out of 5]

Update:
Here is a really good simple diagram of the system. (Click to expand if the print is too small).


Put simply:

A cross section of California, illustrating how San Francisco's summer weather is famously dominated by advection fog. Three key factors:
 1) The jet stream (upper arrows) move relatively warm moist air to the coast of California.
 2) The water just offshore is coming from the far north (due to the Coriolis effect) and chills the moist air above it, creating a long-lasting marine layer.
 3) High summer temperatures in the Central Valley create a low pressure system as the air rises, pulling that marine layer air up the Sacramento River Valley past San Francisco (and other low passes in the Coastal Range).
 The result is fog and winds whenever temperatures are high inland. (Click on the picture below to see this phenomena if you aren’t familiar with it.)

Update: if you want to understand the SF Bay Area climate and microclimates, I found an excellent and much shorter (albeit still longish) explanation here at the Western Regional Climate Center's site. Warning: no diagrams makes it rough going. I used google to poke around on that website and discovered it is linked from their state climate narratives page which — bonus! — provides similar capsule summaries for the state of {Alaska, Arizona, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming}. It appears to be drawn from an NOAA book from 1980, which Google Books knows about, but which isn't listed on Goodreads.

            ☀️🌤⛅️🌥☁️🌬🌦🌧🌪⛈🌩🌨

This slim book is required reading for anyone who lives in or loves San Francisco. It is also highly recommended for anyone who lives in the region affected by San Francisco’s thoroughly confusing summer weather, which can include the entire bay region, the delta, and even much of the central valley and the Sierras.

The book explains why summer weather can look like this…

(Click through for a gorgeous two-minute time-lapse of Karl the Fog!)

There’s no evidence that Mark Twain actually said “The coldest winter of my life was the summer I spent in San Francisco,” but the idea is correct. Several oddities of the geology and climate combine to give San Francisco very curious summer weather: a typical day is chilly and windy, much to the surprise of tourists expecting “California weather.”

The most basic answer is that very hot weather (quite common for six or more months of the year) in the Central Valley sucks air in through the Golden Gate, and the air outside is the cool fog of a marine layer. But the science is fascinating!

This book explains it all.

The regional magazine Bay Nature asked the author to provide a detailed synopsis when his wonderful book was reissued in 2002: Cutting Through the Fog: Demystifying the Summer Spectacle.

Okay, one more glorious photo. The fog keeps those tan-seeking southern Californians out of the city!

­

[Emily]

"This book should be of interest to the many Bay Area residents for whom weather is a matter of daily concern."

you're damn right it is

[Ed Erwin · Rating 4 out of 5]

Yes, the weather here really is unique enough to warrant a whole book! Long live Karl the Fog!

[Ken-ichi · Rating 4 out of 5]

A brief but solid introduction to an endless and airy topic. I would have appreciated a few more diagrams but that is always the case.

[Walter Underwood · Rating 5 out of 5]

I read the first edition when I moved to the SF Bay area decades ago. It helped me understand, and occasionally predict, our local weather. This edition is even more helpful because there is another fifty years of science behind it.

[Jennifer · Rating 5 out of 5]

This book explains everything about the microclimates in and around San Francisco. After reading this I understand much more than anyone has tried to explain to me. For instance, not only are there seasonal cycles of weather patterns, but also weekly and daily patterns that influence the foggy/sunny and rainy/dry weather. The book also relates local weather to bigger phenomena such as the Coriolis effect and the jet stream, without assuming any technical knowledge. There are good maps and diagrams showing, for example, the average annual rainfall across cities and the mountain gaps through which fog enters inland areas.

This book is an updated version that was originally published in 1962. The writing is poetic at times without losing clarity of explanation. The updated version adds references to unusual recent weather events and addresses El Nino and global climate change.

[Scott Cox · Rating 5 out of 5]

This little booklet well describes the unusual weather patterns found in the San Francisco Bay region. San Francisco is one of the few cities with coastal fog that produces cool summer temperatures. For example, on an average summer day, it can be 60 degrees F (~16 degrees C) in San Francisco due to the cooling effects of coastal fog. And only 50 miles inland, on the same day, it might be close to 100 degrees F (~38 degrees C). This is due to "The Pacific High." Also, this booklet explains why the San Francisco Bay Area receives very little summer precipitation (except from coastal fog) which is common to Mediterranean climate regions of the world. This allows for the production of excellent wines in the Napa Valley region. This booklet is part of the very informative University of California Press natural History guide series. All are highly recommended!

[Tyler · Rating 4 out of 5]

This is fun stuff, and reads like a magazine with excellent pictures of fog etc. The level of detail is perfect for sounding like an expert on the subject in conversations without having to get into the less savory details of weather and climate. Definitely a must for anyone that lives in the bay area.

[David Hockabout · Rating 5 out of 5]

Harold Gilliam has boiled down the weather of San Francisco in general and all of the microclimates that effect the region that is concise and readable. Mr. Gilliam looks at such questions as how does the fog develop, Why does Halfmoon Bay receive 29 inches of rain and San Joes receives only 14 inches? Highly recommended.

[Tessa · Rating 3 out of 5]

This book gave me all the answers I wanted about the San Francisco Bay Area fog phenomenon!...why it can be sunny in one part of the city and foggy in another, how the fog develops, the different types of fog, etc. I wouldn't recommend it unless you live here, though.

[Brandon · Rating 3 out of 5]

This is a very niche book. It has a nice intro to weather/climate basics and delves deep into many bay area weather particularities. That said, the production value is disappointingly low, the book is pretty old and out of date (it doesn't even mention the wildfire smoke that regularly chokes the bay area every summer now), is only 99 pages long, and focuses on San Francisco (and especially its fog) to the detriment of the rest of the bay area.

[Rohan Sahai · Rating 4 out of 5]

Fun book to read as a Bay Area resident. Really enjoy how the book is divided into the seasons. Only thing I wish was better summaries of each section - since there is a lot of new information for readers to take in at once

[Steven Aelfcyning · Rating 4 out of 5]

A good introduction to the topic. I would have appreciated more information on how to read weather maps-- I still don't entirely understand why cold fronts and warm fronts are represented the way they are.

[ronny · Rating 5 out of 5]

super concise and informative manual to the weather of the Bay Area, complete with helpful diagrams and way too many photos of fog billowing across the Golden Gate Bridge.

[Sean · Rating 5 out of 5]

If you live in the Bay and are interested in how the weather works, you simply have to get this book. Gilliam explains how the Bay Area's weather patterns come about by weaving together elementary weather science in an understandable and engaging way. If you don't know much about weather, Gilliam (a journalist by trade) explains the concepts you need well enough to get you through. If you already know about cyclones, ridges, troughs, fronts, and the like, this book is a real treat because it shows you a concrete example of how these concepts fit together to create real day-to-day weather.

[subgirl · Rating 5 out of 5]

This is such an excellent overview of such a persistent and changeable character of the Bay Area. This was well before the SF fog had a name or Twitter & Instagram accounts. Call it @KarltheFog 's baby book.

I usually have our copy in our guest room, but after finding his well-written Instagram account I wanted to re-acquaint myself with this enigmatic fellow's origins. He sure is welcome any evening to keep the oppressive heat away.

[Steve · Rating 4 out of 5]

Why does SF have fog? Why does it only rain in the winter here? What's the difference between tule fog and regular fog?

This book gives the answer to those questions and more in a short, highly readable form.

Great fun!

[Srivani · Rating 5 out of 5]

Albeit small, this book taught me a lot about what causes the awesomely variable weather in the region.

[Bob Haar · Rating 5 out of 5]

Fascinating explanation of why the Bay Area has so many micro-climates.

[Curt Hopkins Hopkins · Rating 4 out of 5]

I now know why my water glass gets misty. And why my house, 2.5 miles from Ocean Beach, also gets misty. An easy read.

[Kearstin]

cute little book - I've always wondered about the weather here

[Dave Peticolas · Rating 4 out of 5]

Exactly what the title says, except far more interesting and well-written than it sounds.