3 ms·

Big droughts have come and gone over the years. Here’s a nice historical data explorer: https://www.drought.gov/historical-information?dataset=0&selectedDateUS

• __MatrixMan__ 4y ago
  > The SPI is the number of standard deviations that observed cumulative precipitation deviates from the climatological average Is "the climatological average" the same as https://en.wikipedia.org/wiki/Climatological_normal https://en.wikipedia.org/wiki/Climatological_normal? if so then it's a pretty misleading metic. You can deviate from "normal" in both directions roughly at the same frequency, all the while dragging normal below a "you can survive this" threshold.