The calendar says the middle of October, so having the first widespread freeze is certainly expected for Iowa. For Ames, a new season to date coldest temperature was set. The featured chart looks into the number of times after 1 July and until next year's 30 June that the low temperature was colder than any previous season to date temperature (so called step-downs in low temperature). The top panel presents the number of such events each year. The second panel plots the frequency by temperature and the bottom panel plots the frequency by day of the year. For the bottom panel, the algorithm choice of starting on 1 July causes the initial spike as the spin-up for the season happens. Of interest is that on average, there are only about 20 such dates for the given year. So even with all of the colder half of fall and winter season ahead of us, there are likely only about 10 days left whereby a new coldest of the season low temperature will be set. From the glass is half full department.