Tables: month by month, the stations, and the driest and wettest years (text twin)
Sources. California Department of Water Resources, California Data Exchange Center: the Northern Sierra 8-station, San Joaquin 5-station and Tulare Basin 6-station precipitation indices (daily values, the monthly record and the season summary) and the statewide snowpack summary, as published. DWR publishes the indices daily; this site reads them each morning.
Method. The average for each date is the 1991 to 2020 mean of the monthly record, interpolated within the month; it is the same base period as every published percent of average. The band is computed across every complete water year of the monthly record (1920 onward for the Northern Sierra, 1913 for the San Joaquin, 1922 for the Tulare Basin), each year’s monthly totals accumulated on the same calendar. Water years before the daily record (1998 for the Northern Sierra, 2016 for the other two) are drawn from the monthly record. The kind of year is the Sacramento Valley classification the toolkit uses everywhere. Full rules: definitions .
conciseVerbosity is an independent personal project; the views and tools here are separate from the organizations I serve.