Standardized Precipitation Index Table

Central Basin Climate Division

Washington, Climate Division 08

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.) 0.48 1 2.15 3.61 4.65 7.6 10.36 10.75 10.86 11.02 11.03 11.33 12.93 17.91 21.13 27.02 31.26 41.29 47.94 55.95
Accumulated Precipitation Departure from Normal (in.) -0.27 -0.44 -0.15 0.26 -0.06 1.32 2.63 2.23 1.89 1.78 1.54 1.17 0.47 1.48 0.82 0.44 0.8 0.69 -2.8 -4.96
Accumulated Precipitation Percent of Average 64 69 93 108 99 121 134 126 121 119 116 112 104 109 104 102 103 102 94 92
Accumulated Precipitation Percentile (non-exceedance) 34.1 30.4 48.7 63.1 52.1 80.3 91.2 86.5 82.1 81.4 78.4 72.7 60.4 72.8 62.9 56.9 60.1 57.8 28.3 16.7
Standardized Precipitation Index -0.41 -0.51 -0.03 0.33 0.05 0.85 1.36 1.1 0.92 0.89 0.78 0.6 0.26 0.61 0.33 0.17 0.26 0.2 -0.57 -0.96