A narrow strip along the eastern edge of the County, ranging in width from 6 miles at the north county line to 1 mile at the south county line, is drained by east-flowing tributaries of the Walnut River. Much of the flat land adjacent to the Arkansas River is very poorly drained, and artificial drains have been installed on much of the agricultural land. An extensive flood diversion system has been constructed around Wichita to alleviate recurrent flooding of urban areas by the Little Arkansas and Arkansas rivers and their tributaries. Sedgwick County lies in the path of warm, moist air masses moving northward from the Gulf of Mexico that alternate with cold, dry air moving southward from the polar regions. Consequently, the weather is subject to frequent abrupt changes.
Summers are generally hot.
Winters are usually mild, but snow flurries are common, with snow usually remaining on the ground for a short time only. The average date of the first killing frost in the fall is October 31 and of the last killing frost in the spring April 6, with an average growing season of 208 days. Most of the precipitation falls during the growing season in the form of brief, heavy thunderstorms. The distribution of precipitation throughout the year and from year to year is quite irregular. The wettest year on record at Wichita was 1951 when 50.48 inches of precipitation were recorded.