Des Moines is situated on rolling terrain in south-central Iowa along the banks of the Des Moines River, the longest river in the state and an important tributary of the Mississippi River. Good drainage to the southwest produces fertile farmland, which is surrounded by coal fields. Marked seasonal changes occur in both temperature and precipitation. During winter, snowfall averages more than 30 inches; drifting snow often impedes transportation and sub-zero temperatures are common. Des Moines sits in a tornado zone. The growing season extends from early May to early October; approximately 60 percent of the annual precipitation occurs during this time, with maximum rainfall in late May and June. Autumn is generally sunny and dry, producing favorable conditions for drying and harvesting crops.
Area: 76 square miles (2000)
Elevation: 838 feet above sea level
Average Temperatures: January, 19.4° F; July, 76.6° F; annual average, 49.7° F
Average Annual Precipitation: 33.12 inches of rain, 33.3 inches of snow