Standardized Precipitation Index Table

Northeast Climate Division

Illinois, Climate Division 02

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.) 1.46 7.01 16.27 19.52 23.81 27.94 36.6 40.89 43.3 46.04 48.45 50.7 61.76 75.64 89.9 113.75 133.52 175.41 213.82 252.64
Accumulated Precipitation Departure from Normal (in.) -0.92 1.9 7.66 7.31 7.98 8.06 12.8 13.73 13.65 14.87 15.55 15.75 18.26 20.88 20.15 24.23 28.96 36.16 39.88 44.03
Accumulated Precipitation Percent of Average 61 137 189 160 150 141 154 151 146 148 147 145 142 138 129 127 128 126 123 121
Accumulated Precipitation Percentile (non-exceedance) 27.4 82.5 98.2 96.6 97 95.4 99 99 98.9 99.3 99.5 99.4 99.6 99.6 99.4 99.4 99.7 99.8 99.7 99.7
Standardized Precipitation Index -0.6 0.93 2.11 1.82 1.88 1.68 2.34 2.33 2.3 2.45 2.56 2.51 2.69 2.66 2.49 2.49 2.77 2.9 2.8 2.77