Crook County lies in the central part of Oregon along the Ochoco Mountains. 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 Crook County. Climate tables for various parameters, as observed at long-term climate stations in Crook 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 the Crook 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.

Table 2 lists 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: Oct. 24, 1882
Population: 19,850
Area: 2,991 sq. mi.
Economy: Livestock, forest products, recreation, agriculture, manufacturing and wholesale trade.
County Seat: Prineville

Crook County was formed from Wasco County in 1882, and named for Maj. Gen. George Crook, U.S. Army. Geographically, the county is in the center of Oregon. It is unique in that it has only one incorporated population center, the city of Prineville, founded in 1868. Prineville's colorful past was the scene of Indian raids, range wars between sheepmen and cattlemen and vigilante justice. Other communities in this sparsely settled region are Powell Butte, Post and Paulina. Forest products, agriculture, livestock raising and recreation/tourism services constitute Crook County's total economy. Thousands of hunters, fishers, boaters, sightseers and rockhounds are annual visitors to its streams, reservoirs and the Ochoco Mountains. Rockhounds can dig for free agates, limb casts, jasper and thundereggs on more than 1,000 acres of mining claims provided by the Prineville Chamber of Commerce. Major annual events include the Prineville Rockhound Pow Wow, Crooked River Roundup, Crook County Fair, Old Fashioned Fourth of July Celebration, High Desert Celtic Festival and the Lord's Acre Sale.

Climate Tables (Crook County, Oregon)