Monthly Means and Extremes
Pelton Dam, Oregon Period: 1961-1990
Parameter Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Mean Temperature (F)
Maximum 44.9 52.3 59.6 66.7 75.7 84.5 92.6 91.8 82.7 69.7 53.2 44.6 68.3
Minimum 25.8 28.6 30.9 34.4 40.2 47.0 50.7 50.4 43.7 36.2 31.9 26.5 37.1
Mean 35.3 40.5 45.3 50.6 58.0 65.7 71.7 71.1 63.3 52.8 42.5 35.5 52.6
Extreme Temperature (F)
Maximum 71 78 86 95 108 108 112 112 108 96 79 68 112
Minimum -12 -11 15 18 24 29 36 37 25 14 0 -15 -15
Precipitation (inches)
Monthly mean 1.52 .93 .85 .67 .67 .57 .29 .46 .47 .61 1.50 1.54 10.01
Extreme 24 hour .93 1.15 .70 1.22 .86 .87 .70 .78 1.15 .74 1.80 2.00 2.00
Snowfall (inches)
Monthly mean 1.94 .04 .00 .00 .00 .00 .00 .00 .00 .02 .73 1.15 4.55
Average number of days
Temperature
Maximum 90 or more .0 .0 .0 .3 3.4 10.0 20.4 19.9 8.2 .6 .0 .0 64.8
Maximum 32 or less 3.7 .7 .0 .0 .0 .0 .0 .0 .0 .0 .5 3.2 7.8
Minimum 32 or less 23.7 19.6 18.9 12.7 4.4 .1 .0 .0 1.0 9.9 16.3 24.1 131.4
Minimum 0 or less .7 .3 .0 .0 .0 .0 .0 .0 .0 .0 .0 .6 1.8
Precipitation
.01 inches or more 8.7 8.1 7.9 5.4 5.0 3.7 2.4 3.1 3.5 5.0 9.7 10.2 72.3
.10 inches or more 5.1 2.9 2.9 2.1 2.5 1.7 1.0 1.6 1.4 2.1 4.5 4.6 32.2
.50 inches or more .6 .2 .1 .2 .1 .2 .1 .2 .2 .1 .7 .6 3.3
1.00 inches or more .0 .1 .0 .1 .0 .0 .0 .0 .0 .0 .1 .1 .3
Degree Days
Heating days @ 65F 920 692 612 434 241 77 13 15 105 381 675 916 5109
Growing days @ 50F 2 5 22 90 258 472 672 654 400 134 13 2 2732
Oregon Climate Service