Standardized Precipitation Index Table

Northwest Climate Division

Illinois, Climate Division 01

Precipitation Data Table

Time Scale in Months (As of the end of Mar. 2024)
1 2 3 4 5 6 7 8 9 10 11 12 15 18 24 30 36 48 60 72
Accumulated Precipitation (in.) 3.38 3.72 6.32 9.06 9.85 13.92 17.54 19.68 24.77 26.5 28.9 31.69 39.58 45.4 70.47 83.63 102.07 138.33 187.71 235.04
Accumulated Precipitation Departure from Normal (in.) 0.94 -0.14 0.92 1.85 0.42 1.81 1.75 0.12 1.35 -1.21 -2.83 -3.38 -0.88 -1.84 0.23 1.27 -3.27 -2.2 11.99 24.21
Accumulated Precipitation Percent of Average 138 96 117 126 104 115 111 101 106 96 91 90 98 96 100 102 97 98 107 111
Accumulated Precipitation Percentile (non-exceedance) 79.8 51.3 73.2 82.9 59.9 76 70.4 54 63.7 43.2 32.1 29.4 46.4 40.7 52.7 57 38.9 44.1 80.3 93.7
Standardized Precipitation Index 0.83 0.03 0.62 0.95 0.25 0.71 0.54 0.1 0.35 -0.17 -0.46 -0.54 -0.09 -0.24 0.07 0.18 -0.28 -0.15 0.85 1.53