Standardized Precipitation Index Table

Cascade Mountains West Climate Division

Washington, Climate Division 05

Precipitation Data Table

Time Scale in Months (As of the end of Nov. 2019)
1 2 3 4 5 6 7 8 9 10 11 12 15 18 24 30 36 48 60 72
Accumulated Precipitation (in.) 4.26 12.95 19.49 21.01 22.57 24.99 27.83 35.37 37.99 46.05 54.52 68.95 91.73 95.14 151.25 187.48 251.87 362.5 443.52 547.82
Accumulated Precipitation Departure from Normal (in.) -8.91 -8.05 -5.46 -5.69 -5.53 -6.31 -7.55 -5.84 -12.32 -14.07 -18.67 -18.04 -20.25 -23.21 -22.73 -17.9 -9.05 14.68 9.13 26.82
Accumulated Precipitation Percent of Average 32 62 78 79 80 80 79 86 76 77 74 79 82 80 87 91 97 104 102 105
Accumulated Precipitation Percentile (non-exceedance) 3.3 15.7 28.6 28 28.4 24.5 20 27.6 10 10 6.1 9.1 10.5 7.6 13.1 21.1 37.4 69.2 61.5 76.9
Standardized Precipitation Index -1.85 -1.01 -0.57 -0.58 -0.57 -0.69 -0.84 -0.59 -1.28 -1.28 -1.55 -1.33 -1.26 -1.43 -1.12 -0.8 -0.32 0.5 0.29 0.74