San José State University
Thayer Watkins
Silicon Valley
& Tornado Alley

San José rainfall statistics 1901-1918 and 1934-2014

There has been quite a bit of media propaganda about a megadrought for California that might last 100 years. The current drought is not that much more severe than past droughts that lasted only a few years. Here are the statistics on rainfall in San José.


The data for 1919 through 1933 is missing. There were a few other years for which the data is missing and interpolated values were used for them.

Note the drought that lasted from 1945 to 1949. This is likely connected with the natural 60+ year cycle in average global temperature. From 1940 to 1975 average global temperature was declining. From 1975 to about 2000 the average global temperature was increasing and from 2000 to 2014 the average global temperature has been flat. Global temperature declines because of a cyclic decline in the surface temperature of the Pacific Ocean. The cooler the ocean surface temperature the less evaporation and the less coastal rainfall at least for a while.

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