Palmer Drought Severity Index
Historical Data
Average
Interval:
The Palmer Drought Severity Index uses temperature and precipitation data to calculate relative dryness. The tree rings are colored to represent the stand index. As numbers increase or decrease, the rings are drawn either further apart, to indicate more growth, or closer together, to indicate less growth. Notice the marked increase in drought years since 2000. For more information see technical notes.
2014 
Severe Drought
Scientists estimate that for central and southern California as a whole, 2014 was the single worst year of drought in over 1000 years. It was not only low rainfall, but also high temperatures that resulted in such a severe drought. MORE