Precipitation totals for over 1000 locations in California are available through the California and Nevada River Forecast Center, or CNRFC, on the National Oceanic and Atmospheric Administration's website. This site provides information on recent and past precipitation data.
NOAA provides local precipitation maps and charts through the CNRFC site. To access a chart containing precipitation totals for the past one, six, 12 or 24 hours, users click on the first CNRFC Precipitation Text Products link. To access monthly precipitation data back to 2002, users can click on the link corresponding to the year they'd like to access under the Monthly Observed Precipitation - NWS Cooperative Observers section. All precipitation data on these charts is displayed in inches.
Other Web sources contain simpler but less comprehensive precipitation information. The California Climate Data Archive provides easy-to-read maps showing precipitation and temperature across California for the past seven or 30 days. Reports on the average monthly rainfall state-wide, as well as other climate data, are available through the California Department of Water Resources. Precipitation totals for longer periods of time are available through the Western Regional Climate Center, which provides 30-year totals for precipitation in the state and summary and average data for selected cities dating back to 1949. These historical records can be compared to current precipitation data for analogous cities, or state-wide to compare current precipitation trends with historic trends.