Standardized Precipitation Index Table

North Central Climate Division

Montana, Climate Division 03

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.) 1.46 2.29 2.91 3.8 4.41 4.99 5.75 5.97 8.4 10.53 11.18 13.12 18.45 20.37 28.16 34.85 43.55 53.26 67.02 83.05
Accumulated Precipitation Departure from Normal (in.) -0.74 -1.06 -1.27 -1.02 -1.19 -1.37 -1.37 -2.03 -0.91 -0.1 -0.95 -1.93 -0.79 -1.02 -1.93 -1.56 -1.56 -6.82 -8.05 -7.01
Accumulated Precipitation Percent of Average 66 68 70 79 79 78 81 75 90 99 92 87 96 95 94 96 97 89 89 92
Accumulated Precipitation Percentile (non-exceedance) 28.7 22.2 18.3 25.7 23 20 21.7 11 33.9 50.7 35.3 24.3 41.9 38.9 32 36.4 37.3 8 6.3 10.9
Standardized Precipitation Index -0.56 -0.76 -0.9 -0.65 -0.74 -0.84 -0.78 -1.23 -0.41 0.02 -0.38 -0.7 -0.2 -0.28 -0.47 -0.35 -0.32 -1.41 -1.53 -1.23