As cooler temperatures settle into the region, the annual changing of the leaves will rapidly begin to intensify throughout the area. Throughout southern and central Iowa, peak viewing of fall colors is expected in the middle of October, according to the Iowa DNR. In the state’s weekly report for South Central Iowa, bottomland tree species are starting to change, including walnut, cottonwood, silver maple, bitternut hickory, and elm are turning to yellow and starting to fall. The overall upland landscape is still mostly green as oaks have not started to change yet. Typically, the first frost of fall takes place in the first week of October, however, overnight temperatures are not expected to dip below 40 degrees in the long term forecast.