Article Title

Climate Trends in Iowa

Document Type



Climate change, Climate variability, Heat stress, Growing degree day, Runs of weather


Long-term trends for various weather elements are presented for the period 1900-1988. Summer and winter season, and annual air temperature patterns are statistically weak because of large inrerannual variability, but trends are evident. There was a general warming from 1900 until the 40's, with a leveling or slight cooling following. Since the mid-70's, a warming trend seems to be taking place, but this cannot be confirmed. Spring season air temperatures showed no trend except that the most recent 4 years (1985-1988) were decidedly warmer than normal. Winter season air temperatures showed a change in trend in the 30's, but the large amount of interannual variability during the last 15 years clouds any recent trend. Fall season air temperatures reveal no trends. Derived air temperature variables, growing degree days and the length of the growing season, for the Ames weather station reveal no definite trends. When averaged overall available stations, the length of the growing season seemingly has increased about 1 day/decade. A heat-stress variable shows periods of both stressful and benign time periods during this century. The major benign period was 1957-1975. Before 1957, considerable interannual variability is evident. Years following 1975 may be showing a return to more interannual variations, but extrapolation forward in time is not possible.

Publication Date

September 1990

Journal Title

Journal of the Iowa Academy of Science





First Page


Last Page



© Copyright 1990 by the Iowa Academy of Science, Inc.



File Format