0 OS 5 11/4)c q .ze Unbound issue z Does not circulate c.v P. Special Report 920 May 1993 The Climate of Oregon Climate Zone 8 Northeast Area Property of OREGON STATE UNIVERSITY Library Serials Corvallis, OR 97331-4503 Agricultural Experiment Station Oregon State University For additional copies of this publication, write: George Taylor State Climatologist Oregon Climate Service Strand Agriculture Hall 326 Oregon State University Corvallis, OR 97331-2010 The Climate of Oregon Climate Zone 8 Northeast Area George H. Taylor, State Climatologist Alexi Bartlett Oregon Climate Service Oregon State University Corvallis, Oregon March, 1993 Oregon Climate Zone Summary Zone 8-- Northeast Area Climate Zone 8 occupies the northeastern corner of Oregon, occupying all of Wallowa, Baker, and Union Counties as well as portions of Umatilla and Grant. The area indudes several sizable mountain ranges with large valleys between them. Among the larger cities are La Grande, Baker City, John Day, and Enterprise, although the biggest of these (La Grande) has a population of only slightly above 10,000 residents. Livestock raising is the major industry in this region; several million acres of Federal land are being utilized by ranchers for livestock. Beef cattle raising predominates, but sheep, dairy herds, poultry, and hogs are significant income sources as well. Field crops are also an important farm commodity; important crops include wheat, potatoes, barley, oats, and grass seed. Lumber is also produced in significant quantities from the forested areas in the region. Annual precipitation totals in Zone 8 valley areas are generally below 20 inches. Some locations surrounded by high mountains, such as Baker City and Unity, barely exceed 10 inches per year. High elevation sites, on the other hand, receive much larger annual totals. Locations near the top of the Wallowa Mountains, for example, may exceed 100 inches precipitation per year, much of it in the form of snow. Table 1 lists monthly and annual Ci Walla Walla Scale of miles 64666mfo 40 so Wallowa Elgin 0 0 La Grande 0 OCove 0 Union Exp Stn 0 Ukiah Rock CreekO OHalfway 0 Baker j 0 ORichland Monument 0 Long Creek QAustin John Day Unity 0 Huntington '4\4S ,,,,0Seneca normal precipitation at Zone 8 sites. Highest normal precipitation totals tend to be in winter and late spring. Unlike most of Oregon, Zone 8's monthly distribution in comparison is remarkably uniform throughout the year. Zone 8's distance from the ocean causes its annual temperature variations to be rather large. Table 2 lists normal monthly precipitation at stations in the area. Mean maximum temperatures are mostly in the 80's in summer months and in the 30's in winter. The dry, dear summer days are usually followed by cool nights; nighttime lows generally average in the 40's. The coldest temperatures in the region (and probably in the state) are observed in Seneca, located in a deep valley surrounded by mountain ridges. January low temperatures in Seneca average a cold 8.4°F. Annually, Seneca experiences an average of 22 days with below-zero temperatures. Seneca is in a tie for the coldest temperature ever recorded in Oregon, -54°F, set in February 1933. Tables 3 and 4 list median frost dates and mean growing seasons, respectively, for four different temperature thresholds. While some of the lower valley sites have fairly long growing seasons, a few of the colder locations have a very short season. At Seneca, Austin, and Ukiah, the mean length of time between freezing temperatures is less than six weeks. Oregon Climate Service 1993 Oregon Climate Zone 8 Northeast Area Table 1. Monthly and Annual Precipitation (inches) 1961-1990 Means Elevation Name (feet) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Austin 4200 2.78 1.94 1.98 1.44 1.47 1.62 .72 1.01 1.06 1.32 2.55 3.08 20.49 Baker 3471 1.03 .62 .84 .82 1.26 1.38 .58 .94 .74 .63 .96 1.07 10.87 Cove 3120 2.53 1.22 2.59 2.61 3.24 2.17 .42 1.52 .69 1.23 2.49 1.27 22.47 Elgin 2660 2.98 2.46 2.27 1.68 1.72 1.46 .65 .86 1.05 1.72 3.13 3.52 23.73 Enterprise 3880 1.44 .76 1.89 1.56 2.09 1.59 1.01 1.76 .52 .55 1.51 .84 15.53 Halfway 2670 3.28 2.31 1.92 1.40 1.37 1.31 .47 .76 .92 1.31 3.02 3.50 21.58 Huntington 2130 1.78 1.36 1.27 .81 .91 .94 .38 .67 .60 .79 1.81 2.06 13.57 John Day 3060 1.15 .82 1.12 1.18 1.56 1.40 .53 .95 .84 .92 1.47 1.40 13.38 La Grande 2760 1.96 1.47 1.48 1.42 1.61 1.43 .63 .92 .97 1.24 1.86 1.86 17.18 Long Creek 3720 1.46 .93 1.42 1.33 1.46 1.24 .61 .86 .84 1.20 1.67 1.58 14.34 Monument 2000 1.48 1.03 1.33 1.31 1.38 1.08 .46 .74 .68 .92 1.51 1.53 13.73 Richland 2220 1.53 .91 .91 .96 1.22 1.02 .63 .85 .57 .71 154 1.39 12.59 Rock Creek 7250 2.67 1.89 1.87 1.37 1.65 1.78 .92 .98 .92 1.20 2.54 2.91 20.66 Seneca 4660 1.29 1.03 1.17 .99 1.34 1.11 .55 .87 .66 .88 1.49 1.67 13.12 Ukiah 3360 1.93 1.30 1.42 1.32 1.63 1.21 .63 .85 .88 1.22 2.08 1.99 16.19 Union 2770 1.16 .90 1.18 1.24 1.64 1.56 .61 .94 1.04 1.00 1.32 1.19 13.79 Unity 4030 1.23 .67 .76 .68 1.08 1.14 .44 .92 .54 .57 1.16 1.28 10.91 Walla Walla 2400 6.22 4.20 4.71 3.53 2.70 2.10 .69 1.17 1.86 3.19 5.69 5.26 41.09 Wallowa 2920 1.94 1.34 1.40 1.25 1.69 1.41 .85 .90 1.25 1.43 1.88 2.00 17.15 Oregon Climate Service 1993 Oregon Climate Zone 8 Northeast Area Table 2. Monthly Temperatures (°F) 1961-1990 Means Station Code Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann Austin Mean Maximum 34.6 40.5 45.9 54.3 62.6 72.0 81.6 81.6 71.2 60.2 43.1 34.7 56.1 Mean Minimum 10.5 14.6 19.5 25.6 30.7 37.1 39.2 38.1 30.5 24.9 20.9 12.1 24.8 Monthly Mean 22.5 27.6 32.7 40.0 46.5 54.5 60.4 59.9 50.9 42.6 31.9 23.4 40.3 Baker Mean Maximum 33.7 41.1 50.0 58.8 67.2 75.8 84.9 84.3 74.7 62.5 45.7 35.3 59.5 Mean Minimum 16.8 22.4 26.9 31.1 38.1 45.0 48.5 47.4 38.9 30.5 25.1 17.7 32.4 Monthly Mean 25.3 31.8 38.5 45.0 52.6 60.4 66.7 65.8 56.8 46.5 35.4 26.5 45.9 Cove Mean Maximum 38.0 37.1 51.4 61.2 63.6 74.2 85.2 81.1 77.5 63.6 48.3 36.9 59.6 Mean Minimum 23.6 16.6 28.1 35.0 37.2 43.9 48.7 46.9 41.0 35.9 30.1 18.8 33.9 Monthly Mean 30.8 26.9 39.7 48.1 50.4 59.0 67.0 64.0 59.3 49.8 39.2 27.8 46.7 Elgin Mean Maximum 37.9 44.8 52.0 60.8 69.3 78.3 87.6 87.8 78.1 65.2 47.8 38.6 62.4 Mean Minimum 21.6 25.4 28.5 32.0 37.5 43.6 46.0 45.1 37.7 31.3 28.3 22.8 33.3 Monthly Mean 29.7 35.1 40.3 46.4 53.4 61.0 66.8 66.4 57.9 48.3 38.1 30.7 47.9 Enterprise Mean Maximum 33.2 37.5 47.7 60.0 61.6 70.8 78.3 76.9 73.7 62.1 44.8 33.9 56.7 Mean Minimum 12.2 13.3 23.4 29.4 33.4 39.8 41.4 39.3 33.3 26.9 22.3 11.9 27.2 Monthly Mean 22.7 25.4 35.5 44.7 47.5 55.3 59.9 58.1 53.5 44.5 33.5 22.9 42.0 Halfway Mean Maximum 32.7 40.3 51.0 61.9 70.8 79.2 88.1 87.1 77.3 64.6 46.4 34.5 61.2 Mean Minimum 14.4 19.0 25.8 30.9 37.0 43.7 47.6 46.5 38.6 30.5 25.3 16.8 31.3 Monthly Mean 23.6 29.7 38.4 46.4 53.9 61.5 67.8 66.8 58.0 47.6 35.9 25.7 46.3 Huntington Mean Maximum 35.6 44.1 55.1 64.7 74.2 84.1 93.6 92.0 80.1 66.5 48.8 37.6 64.7 Mean Minimum 19.8 25.3 31.6 38.3 46.8 55.9 63.8 61.4 49.8 38.0 29.2 21.6 40.1 Monthly Mean 27.7 34.7 43.3 51.5 60.5 70.0 78.7 76.7 65.