Harney County is the largest county in Oregon. It is an arid region with a low annual precipitation of about 10 inches/year. In the basin, the precipitation is even lower (8.75 in/year). The temperature in the county varies greatly with a record low of -40 degrees and a high of 105 degrees. The growing season is short due to frost which can occur during any month. Usually, killing frosts stop in the middle of June and begin in late August. The average time between killing frosts is 72 days but there are great variations between the duration of the period and the dates of the frosts. These factors limit the crops that can be grown to hardy hay and cereal crops.