The climate of Dewey County is semiarid and is characterized by cold winters, hot summers, and little winter precipitation. Growing season rainfall is marginal for adapted crops. The recently formed Lake Oahe extending along the eastern border of the county may have some small effect on climate in its immediate vicinity. Elsewhere in the county, the climate is not affected by bodies of water or other physical features.
Temperature varies widely seasonally and occasionally differs significantly from day to day. Temperature readings above 100 degrees (F) in summer and lower than 30 degrees below zero (F) in winter have been recorded. Readings reach 100 degrees of higher on an average of 6 days per year. A reading of 30 degrees below zero or lower may be expected on an average of 2 days in 3 years. A temperature of 20 degrees below zero or lower can be expected on an average of 5 days per year. The average temperature can be expected to drop to zero or lower on about 34 days per year and fall to climb above zero on about 5 days per year.
2014 Spring Flood Risk
LINK TO NOAA SPRING OUTLOOK
No Predicted drought risk for Dewey County as of April 2014
LINK TO SOUTH DAKOTA DROUGHT MONITOR
Climate Change Impacts in the Great Plains
Although all of the region can experience sweltering summers and cold winters, northern portions are known for their bitterly cold and snowy winters. Nevertheless, during the last 30 years, northern portions of the region have seen average winter temperatures rise to 7°F above historical averages. Average year-round temperatures are also increasing. During this century, temperatures are projected to continue increasing, especially in the southern and central Great Plains during the summers. Projections for future precipitation patterns vary within the region. Northern areas may become wetter while southern areas may become drier, especially during the summer.
LINK TO CLIMATE IMPACTS IN THE GREAT PLAINS