Average Statewide Precipitation For Western U.S. States

These statewide averages are obtained as follows: Each state is divided into climate divisions and an average precipitation value is calculated for each division. These division averages are then weighted by the amount of area within each division.

Source: National Climatic Data Center, Historical Climatography Series 4-2.

State       Normals    Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec  | Annual

            1931-60   1.57  1.31  1.17   .99  1.19  1.44  2.23  3.18  2.79  2.59  1.92  1.63  |  22.00
Alaska      1941-70   1.46  1.35  1.28  1.09  1.21  1.56  2.39  3.21  2.77  2.48  1.84  1.67  |  22.29
            1951-80   1.37  1.31  1.19  1.11  1.18  1.65  2.34  3.00  2.73  2.51  1.89  1.67  |  21.94
            1961-90   1.50  1.25  1.17  1.10  1.18  1.69  2.32  2.86  2.76  2.56  1.84  1.78  |  22.01
            1971-00   1.63  1.29  1.20  1.04  1.21  1.67  2.23  2.88  2.88  2.59  1.99  1.89  |  22.50

            1931-60   1.09  1.16   .93   .60   .29   .35  1.69  2.24  1.19   .87   .67  1.13  |  12.20
Arizona     1941-70   1.02   .83   .98   .57   .27   .30  1.75  2.16  1.08   .85   .70  1.17  |  11.69
            1951-80   1.13   .92  1.09   .53   .34   .33  1.78  2.05  1.07  1.03   .81  1.12  |  12.20
            1961-90   1.10  1.01  1.19   .54   .35   .29  1.86  2.07  1.34  1.06   .99  1.30  |  13.10
            1971-00   1.30  1.25  1.35   .54   .42   .31  1.74  2.09  1.30  1.20   .96  1.12  |  13.59

            1931-60   4.07  3.79  2.93  1.69   .84   .32   .12   .17   .34  1.21  2.04  3.95  |  21.47
California  1941-70   4.16  3.25  2.76  1.83   .78   .31   .13   .22   .30  1.22  2.77  3.87  |  21.61
            1951-80   4.35  3.32  2.72  1.67   .70   .28   .17   .29   .47  1.11  2.62  3.58  |  21.27
            1961-90   3.77  3.28  3.13  1.52   .61   .27   .18   .35   .58  1.25  3.14  3.35  |  21.43
            1971-00   4.15  3.95  3.55  1.40   .83   .32   .19   .30   .58  1.20  2.62  3.10  |  22.18

            1931-60    .83   .85  1.13  1.59  1.86  1.35  1.75  1.81  1.21  1.09   .74   .76  |  14.98
Colorado    1941-70    .82   .74  1.11  1.50  1.81  1.58  1.93  1.94  1.21  1.22   .78   .79  |  15.43
            1951-80    .81   .72  1.07  1.32  1.81  1.36  1.90  1.83  1.21  1.09   .84   .83  |  14.78
            1961-90    .72   .72  1.20  1.27  1.80  1.51  2.03  1.87  1.42  1.13   .93   .87  |  15.47
            1971-00    .79   .75  1.29  1.47  1.92  1.44  2.01  1.95  1.35  1.20   .99   .76  |  15.93

Hawaii      1961-90   7.19  5.96  7.69  7.85  5.34  3.44  4.86  4.58  3.98  5.04  7.44  6.96  |  70.33
            1971-00   6.64  5.06  7.15  6.39  4.27  3.59  4.79  4.27  4.05  4.73  6.92  5.85  |  63.70

            1931-60   2.18  1.87  1.76  1.44  1.68  1.59   .60   .59   .92  1.58  1.94  2.33  |  18.47
Idaho       1941-70   2.32  1.75  1.59  1.49  1.84  1.91   .57   .79  1.02  1.54  2.11  2.34  |  19.26
            1951-80   2.47  1.70  1.59  1.49  1.74  1.68   .66   .93  1.05  1.34  1.87  2.33  |  18.86
            1961-90   2.22  1.68  1.69  1.50  1.77  1.64   .82   .96  1.19  1.29  2.07  2.19  |  19.02
            1971-00   2.12  1.72  1.73  1.56  1.97  1.50   .92   .84  1.08  1.30  2.05  2.12  |  18.92

            1931-60    .73   .66   .86  1.13  1.87  2.79  1.33  1.17  1.15   .99   .80   .77  |  14.25
Montana     1941-70    .83   .64   .79  1.24  2.09  3.01  1.37  1.26  1.29   .93   .86   .79  |  15.11
            1951-80    .93   .68   .78  1.32  2.22  2.61  1.36  1.37  1.26   .96   .82   .85  |  15.16
            1961-90    .88   .62   .88  1.27  2.36  2.43  1.46  1.38  1.44   .95   .82   .85  |  15.34
            1971-00    .80   .60   .90  1.30  2.34  2.40  1.65  1.35  1.33  1.05   .85   .78  |  15.34

            1931-60    .95   .89   .81   .79   .78   .53   .47   .40   .38   .68   .68   .90  |   8.25
Nevada      1941-70    .91   .80   .77   .78   .82   .76   .49   .51   .40   .60   .83   .93  |   8.59
            1951-80    .94   .82   .81   .75   .87   .72   .53   .58   .53   .57   .74   .88  |   8.75
            1961-90    .87   .84   .94   .78   .90   .73   .58   .72   .68   .67   .89   .86  |   9.46
            1971-00    .96   .92  1.09   .76  1.01   .63   .51   .63   .71   .75   .81   .72  |   9.50

            1931-60    .63   .60   .64   .69  1.14  1.04  2.13  2.28  1.59  1.12   .48   .64  |  12.99
New Mexico  1941-70    .56   .50   .64   .63   .93  1.03  2.28  2.37  1.49  1.11   .43   .68  |  12.65
            1951-80    .57   .52   .61   .54   .89   .96  2.27  2.38  1.53  1.15   .56   .62  |  12.59
            1961-90    .59   .60   .63   .57   .92  1.17  2.27  2.58  1.87  1.17   .73   .75  |  13.85
            1971-00    .67   .60   .71   .63  1.11  1.23  2.27  2.64  1.82  1.34   .80   .76  |  14.58

            1931-60   3.94  3.16  2.95  1.83  1.83  1.52   .43   .42   .99  2.41  3.44  4.20  |  27.12
Oregon      1941-70   4.24  2.98  2.74  1.81  1.91  1.52   .42   .60   .98  2.50  3.86  4.37  |  27.91
            1951-80   4.40  2.95  2.90  1.87  1.73  1.27   .41   .76  1.08  2.15  3.70  4.47  |  27.70
            1961-90   3.90  2.94  2.92  1.94  1.64  1.26   .52   .82  1.13  1.99  4.01  4.26  |  27.33
            1971-00   3.79  3.16  2.93  2.18  1.88  1.27   .62   .73  1.07  1.90  3.89  3.97  |  27.38

            1931-60   1.02   .99  1.06   .99   .92   .69   .81  1.01   .73  1.07   .84  1.03  |  11.17
Utah        1941-70    .96   .88  1.02  1.07   .91   .88   .75  1.10   .76  1.06   .92  1.06  |  11.37
            1951-80   1.01   .92  1.01  1.02   .97   .68   .77  1.01   .83   .98   .90   .94  |  11.04
            1961-90    .90   .89  1.15  1.07  1.04   .71   .91  1.06  1.07  1.12  1.00   .91  |  11.88
            1971-00   1.05   .99  1.21  1.07  1.20   .64   .88  1.02  1.07  1.30   .97   .80  |  12.22

            1931-60   5.28  4.17  3.78  2.41  1.97  1.94   .74   .86  1.76  3.72  5.18  6.11  |  37.92
Washington  1941-70   5.52  4.12  3.48  2.57  1.88  1.79   .74  1.04  1.78  3.74  5.34  5.86  |  37.98
            1951-80   5.97  4.16  3.65  2.51  1.92  1.60   .79  1.24  1.81  3.25  5.19  6.34  |  38.41
            1961-90   5.59  4.20  3.71  2.58  2.04  1.60   .91  1.16  1.78  3.06  5.54  5.97  |  38.14
            1971-00   5.38  4.37  3.76  2.71  2.23  1.76  1.02  1.05  1.65  3.05  5.69  5.76  |  38.44

            1931-60    .68   .66   .95  1.44  1.86  1.76  1.13   .96   .96   .93   .72   .65  |  12.71
Wyoming     1941-70    .67   .59   .85  1.37  1.90  2.10  1.05   .96  1.04   .90   .73   .66  |  12.83
            1951-80    .68   .57   .79  1.32  1.92  1.74  1.10  1.02   .96   .86   .65   .64  |  12.25
            1961-90    .63   .55   .82  1.33  1.94  1.71  1.24  1.01  1.17   .91   .73   .65  |  12.69
            1971-00    .63   .57   .86  1.36  2.06  1.58  1.33  1.02  1.15  1.04   .74   .59  |  12.92