Standardized Precipitation Index Table

South Central Climate Division

Montana, Climate Division 05

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.) 2.74 5.77 7.11 8.92 10.18 10.91 11.65 12.33 14.12 15.4 16.27 17.56 25 27.17 40.98 49.32 58.49 73.94 89.75 109.15
Accumulated Precipitation Departure from Normal (in.) 0.02 1.22 1.26 2.16 2.4 2.18 1.84 1.11 1.39 1.49 1.03 -0.2 1.4 0.7 5.47 5.09 5.25 2.98 1.08 2.75
Accumulated Precipitation Percent of Average 101 127 121 132 131 125 119 110 111 111 107 99 106 103 115 112 110 104 101 103
Accumulated Precipitation Percentile (non-exceedance) 56.6 80.6 80.4 90.2 91.1 87.7 83 72.2 74.2 75.1 67.7 49.2 67.8 59.8 89.4 85.6 83.6 68.5 56.8 63.7
Standardized Precipitation Index 0.17 0.86 0.86 1.29 1.35 1.16 0.95 0.59 0.65 0.68 0.46 -0.02 0.46 0.25 1.25 1.06 0.98 0.48 0.17 0.35