Standardized Precipitation Index Table

East Slope Cascades Climate Division

Washington, Climate Division 06

Precipitation Data Table

Time Scale in Months (As of the end of May 2025)
1 2 3 4 5 6 7 8 9 10 11 12 15 18 24 30 36 48 60 72
Accumulated Precipitation (in.) 0.8 1.96 6.33 10.34 12.22 19.79 26.4 28.48 28.96 30.6 30.7 32.11 37.1 52.91 62.74 82.78 94.43 133.76 168.16 202.13
Accumulated Precipitation Departure from Normal (in.) -0.95 -1.92 -1.12 -1.46 -5.4 -4.05 -3.22 -4.07 -5.01 -4.14 -4.69 -4.77 -7.24 -7.86 -11.08 -14.9 -16.33 -13.97 -16.51 -19.48
Accumulated Precipitation Percent of Average 46 51 85 88 69 83 89 87 85 88 87 87 84 87 85 85 85 91 91 91
Accumulated Precipitation Percentile (non-exceedance) 12.5 7 34.5 34.8 7.7 20.7 30.8 27.4 22.8 27.2 24.3 23.8 14.6 16.8 10.7 7.9 7.3 15 13.9 11.8
Standardized Precipitation Index -1.15 -1.48 -0.4 -0.39 -1.43 -0.82 -0.5 -0.6 -0.75 -0.61 -0.7 -0.71 -1.06 -0.96 -1.25 -1.41 -1.45 -1.03 -1.09 -1.18