Was this spring really windier than usual?
CONTRA COSTA COUNTY, CA — Over the last several months, the most popular weather-related statement I’ve heard from local residents is: “This the windiest period I’ve ever experienced in the Bay Area.”
I have to admit that I share that feeling, but will data support that perception?
As anyone with a weather app on their phone or computer can attest, there are many locations in Contra Costa County that report current wind conditions. Even with all this available data, verifying our perception is difficult.
The main problem is that very few wind stations have been reporting data for more than a few years. It takes many years (15-30) to collect enough data to make meaningful statistical comparisons. Since wind data are very site-specific, cobbling together a dataset from multiple sites will not produce credible results.
Airport data
Fortunately, the Concord Airport weather station (station ID=CCR) has a long period of records. Even though that station reports hourly wind data, only the daily and monthly values are readily available to the public.
In a simple attempt to evaluate recent wind data in a historical perspective, monthly wind speeds records were reviewed. Specifically, the CCR average wind speeds for the months of April, May and June 2000 to 2021 were ranked from highest to lowest.
The results of this comparison won’t surprise many. For the combined three-month period, the average wind speed at CCR ranked the highest (windiest) for the 22-year period. For the individual months, April ranked No. 1, while May and June ranked third and fourth highest, respectively.
The obvious question that comes from this analysis is: Why has it been so windy this year? CCR data also provide some clues.
CCR daily wind direction data from 2021 indicate that persistently strong sea breeze conditions accounted for a majority of the local high wind events. Sea breeze winds strengthen when several meteorological factors combine.
Jet stream and marine layer
The interaction between the jet stream and the marine layer of air near the California coast is of primary importance. When jet stream is active, meaning that high- and low-pressure systems move in a steady stream across the Pacific, the depth of the cool marine fluctuates in response.
Deep marine layer conditions increase the surface pressure gradient between the cool coast and the hot Central Valley, and sea breeze winds strengthen in response. A quick inspection of weather maps indicates that active jet stream conditions have persisted since the beginning of spring.
Another factor contributing to the coast-inland pressure gradient is sea surface temperature. Cooler ocean temperatures generate larger pressure gradients and stronger winds. Monthly data show coastal ocean temperatures have been cooler than normal all this year.
Concord Airport wind data support the contention that the persistent winds we’ve recently experienced could be a once-in-a-generation occurrence. It appears that an abnormally strong sea breeze is the root cause of the blustery conditions.
Woody Whitlatch is a meteorologist retired from PG&E. Email your questions or comments to clayton_909@yahoo.com
Woody Whitlatch
Woody Whitlatch is a meteorologist retired from PG&E. Email your questions or comments to
clayton_909@yahoo.com