Standardized Precipitation Index Table

Northwest Climate Division

Iowa, Climate Division 01

Precipitation Data Table

Time Scale in Months (As of the end of Jul. 2020)
1 2 3 4 5 6 7 8 9 10 11 12 15 18 24 30 36 48 60 72
Accumulated Precipitation (in.) 1.94 5.36 9.35 10.4 12.96 13.27 14.26 15.75 17.62 22.32 26.83 29.16 44.8 53.41 72.5 96.57 111.61 143.28 182.93 209.66
Accumulated Precipitation Departure from Normal (in.) -1.62 -2.66 -2.62 -4.26 -3.27 -3.8 -3.47 -2.84 -2.26 0.49 1.77 0.52 4.17 7.68 15.23 22.26 25.85 29.07 40.28 38.68
Accumulated Precipitation Percent of Average 55 67 78 71 80 78 80 85 89 102 107 102 110 117 127 130 130 125 128 123
Accumulated Precipitation Percentile (non-exceedance) 18.7 15.9 20.8 9.6 18.6 15.7 18.1 24.2 30 57 66.7 56.5 75.1 86.5 97.4 99.1 99.5 99.3 99.9 99.7
Standardized Precipitation Index -0.89 -1 -0.81 -1.3 -0.89 -1.01 -0.91 -0.7 -0.53 0.18 0.43 0.16 0.68 1.11 1.95 2.37 2.56 2.45 2.99 2.71