Temperatures started off warm Tuesday morning and warmed into the 80s for almost all of Iowa. For Des Moines, the warm-up was 21 degrees between a 9 AM temperature of 63°F to a 5 PM temperature of 84°F (hourly obs listing. The featured chart takes a bit of a deep dive into air temperature changes between 9 AM and 5 PM based on hourly Des Moines airport data. The chart partitions the data by week of the year and plots the frequency of a given temperature change. Negative values indicate a cooler 5 PM temperature than 9 AM of the same day. Values plotted in tan indicate no observations at the given temperature change and week combination. The dashed line is a 14 day smoothed climatology and blue line are 2026 observations, also smoothed to reduce daily noise. The highest frequencies are shown during the summer months when elevated humidity levels reduce temperature variability. The fall season has the largest heating values on average as residual soil warmth from summer and decreased humidity allow for stronger daytime heating.