Introduction

Wheeler County lies along the northern part of theOchoco Mountain Range. It is wholly within Climate Division 7 (South Central Oregon) established by the National Climatic Data Center. Below is a description of the climate of Division 7 followed by specific descriptions of Wheeler County. Climate tables for various parameters, as observed at long-term climate stations in Wheeler County, are included below.

Climate Division 7 — South Central Oregon

South Central Oregon, the largest of the Oregon climatic divisions, is a vast area of high desert prairie punctuated by a number of mountain ranges and isolated peaks. This region is predominantly livestock country; in addition to beef cattle, there are large numbers of sheep, dairy herds, horses, and swine. There are large amounts of land under irrigation as well, particularly in the Deschutes, Crook, Jefferson, and Klamath Counties. Among the major field crops grown are potatoes, alfalfa and other hay crops, mint, wheat, oats, barley, and onions. In the remaining counties comprising this zone (Grant, Harney, and Lake), irrigated acreage is much smaller; grazing lands and dry land farming predominate.

Figure 1 shows NOAA climate stations in Zone 7, which were in operation during the 1961-90 period. Figure 2 shows theWheeler County region from the Oregon annual precipitation map. Most of this region receives relatively low amounts of precipitation. As can be seen in Table 1, most of the stations in Zone 7 receive less than 15 inches per year. However, some of the higher mountain sites receive significantly greater precipitation. For example, Steens Mountain in Harney County, whose summit is more than 9,000 feet above sea level, receives more than 40 inches per year at its higher elevations. Other mountainous locations are also known to receive high annual amounts. Most of the stations in Zone 7 receive their highest monthly precipitation in the winter months with a secondary maximum during late spring and early summer. For other locations, the precipitation is greatest during spring and summer. Stations near the Cascades (such as Sisters, Bend, Chiloquin, Klamath Falls, and Madras) tend to have annual distributions very similar to those in western Oregon: winter maximum are followed by a steady decrease, with lowest monthly averages in midsummer. Farther east, however, spring-summer peaks are much more pronounced. At Hart Mountain, for example, the four wettest months are March through June. The months of July through September are generally the driest of the year throughout the region. These months are characterized by isolated local thunderstorms. Some months are very wet and others almost completely dry.

Tables 2a and 2b list the average number of days with precipitation amounts exceeding certain thresholds.

Table 3 lists normal monthly temperatures for Zone 7 measurement stations. Summers are generally quite warm, although the relatively high elevations tend to moderate the temperatures somewhat. Pelton Dam and Dayville, with mean maximum temperatures in the 90's during the warmest summer months, are the hottest stations in this region. The coldest sites listed are Brothers, Hart Mountain, Sprague River, and Ochoco Ranger Station. It is certain that some of the higher elevations are colder than the areas listed here, however.

Table 4 lists average monthly and annual snowfall total for the various stations.

Tables 5 and 6 list median frost dates and mean growing seasons, respectively, for four different temperature thresholds.

Table 7 and 8 list average monthly and annual heating and growing degree days, respectively.

County Description

Established: Feb. 17,1899
Population: 1,550
Area: 1,713 sq. mi.
Economy: Livestock and tourism.
County Seat: Fossil

Wheeler County was formed by the Oregon Legislature in 1899 from parts of Grant, Gilliam and Crook counties and was named for Henry H. Wheeler, who operated the first mail stage line from The Dalles to Canyon City. The new county consisted of 1,656 square miles with an estimated 46 townships, a population of 1,600 and taxable property worth one million dollars. Wheeler County is as rugged and uneven as any Oregon county, with the terrain varying widely from sagebrush, juniper and rim rock to stands of pine and fir. Portions of two national forests lie within its boundaries with forest lands covering nearly one-third of the county. The area is probably best known as one of the most outstanding depositories of prehistoric fossils on the North American continent.

(County information obtained from Oregon Blue Book)

Climate Tables (Wheeler County, Oregon)