These data maps from NOAAView show estimates of rainfall in California during the month of February in 2015 (l), 2016 (c), and 2017 (r). As is evident from the deeper shade of blue in the image on the right, the state received far more rainfall this year than in the two previous years.
Estimates of rainfall like those shown here are calculated with microwave and infrared data from polar-orbiting and geostationary satellites. This type of data is especially important for monitoring offshore precipitation events before they impact land. In general, the highest rainfall totals are found in tropical areas, where warm water and air temperatures create belts of precipitation.
These estimates correspond with data from ground stations that also show increased rain in the state. According to news website KPBS.org rains in the state have been 142 percent of normal, meaning that, since October 1, California has received well more than a season’s worth of rain (the state’s wet season lasts from Oct. 1 to April 1). During the month of February, the state’s rains were 95 percent of normal.
Link to full article: https://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=2003&MediaTypeID=1