Standardized Precipitation Index Table

Southeast Climate Division

Illinois, Climate Division 09

Precipitation Data Table

Time Scale in Months (As of the end of Jan. 2026)
1 2 3 4 5 6 7 8 9 10 11 12 15 18 24 30 36 48 60 72
Accumulated Precipitation (in.) 1.45 2.66 4.67 8.72 11.46 12.22 16.28 21.55 26.37 35.87 38.44 41.57 52.42 61.18 84.1 101.38 125.37 167.47 212.85 263.79
Accumulated Precipitation Departure from Normal (in.) -1.94 -4.17 -5.74 -4.8 -5.38 -8.06 -7.85 -6.61 -6.27 -1.12 -2.89 -2.66 -2.35 -3.48 -4.46 -7.64 -7.56 -9.81 -8.74 -2.15
Accumulated Precipitation Percent of Average 43 39 45 64 68 60 67 77 81 97 93 94 96 95 95 93 94 94 96 99
Accumulated Precipitation Percentile (non-exceedance) 16.5 3.6 2.7 11.2 11.6 4.7 6.6 12.8 16.7 46.1 36.5 38.1 41.3 37.3 35.2 28 29.6 27.4 31.9 46.6
Standardized Precipitation Index -0.97 -1.8 -1.92 -1.22 -1.2 -1.68 -1.51 -1.13 -0.97 -0.1 -0.34 -0.3 -0.22 -0.32 -0.38 -0.58 -0.54 -0.6 -0.47 -0.09