SAN FRANCISCO — Barely a week after San Francisco saw its first ever Tsunami Warning, S.F. residents were awoken early Saturday morning to another alert first: a Tornado Warning.
Just before 6 a.m. Saturday morning, radar indicated rotation near the Golden Gate on the northwest side of the peninsula, prompting meteorologists at the National Weather Service Bay Area to issue a Tornado Warning for San Francisco, something that had never been done before.
The Iowa Environmental Mesonet at Iowa State University has extensive archives of National Weather Service products.
This data shows that Contra Costa and Santa Clara counties most recently saw Tornado Warnings in 2010; San Mateo County had a warning most recently in 2011; and San Benito, Santa Cruz, and Monterey counties were under warnings earlier this year. Notably, San Francisco City and County had never seen a Tornado Warning before today.
The first Tornado Warning was issued in Oklahoma in 1948. By the 1970s, the National Weather Service began issuing Tornado Warnings in near real-time. In 2006, the National Weather Service updated its alerting protocol, which is the standard we still use today. So, although the map below only goes back to 2006, we have records going back further.
San Francisco's most recent encounter with a tornado—prior to Saturday—was in 2005, when a tornadic storm moved through South San Francisco and Daly City, both of which are in San Mateo County.
A History of Tornadoes Near San Francisco
- December 1891 in San Francisco
- Unrated, Damage unknown
- Unrated, Damage unknown
- April 1, 1958 near San Francisco International Airport in San Mateo County
- Unrated, Damage unknown
- Unrated, Damage unknown
- June 1, 1958 in Marin County
- F2, Traveled 15 miles into Sonoma County causing $25,000 worth of damage
- F2, Traveled 15 miles into Sonoma County causing $25,000 worth of damage
- March 10, 1986 near Moss Beach in San Mateo County
- F0, Waterspout moved ashore flipping a car and damaging a restaurant
- F0, Waterspout moved ashore flipping a car and damaging a restaurant
- December 23, 1996 in Marin County
- F1, Knocked over telephone poles, blew roof off house, collapsed a barn
- F1, Knocked over telephone poles, blew roof off house, collapsed a barn
- March 20, 2005 in South San Francisco in San Mateo County
- F1, Damage to about 60 buildings