Many Iowans woke up to a frosty morning today, and state climatologist Harry Hillaker said it’s right on time. The first below-freezing temps of this autumn hit a lot of places. Hillaker says western parts of the state were in the middle of the cold-air mass, particularly the coldest spot, where Onawa near Council Bluffs recorded the lowest official temperature at 28 degrees. The cold reached clear to the Missouri border and brought overnight lows of 29 at Clarinda and 31 at Chariton. Hillaker says this time of year, we often get big swings in the weather. While we often get both, he says 30s are a bit more typical so late in September — but about a week ago they recorded 101 degrees in Glenwood. Hillaker says despite the last-minute dip, September’s on track to be the warmest since 1939. It’ll probably go into the books among the top ten warmest Septembers, maybe even fourth, fifth or sixth warmest in 133 years of state records. Today’s warmup will continue, as Hillaker says we can expect a week of more weather that’s warmer than typical this time of year. It’s been drier than normal, especially in the southern parts of the state. For much of this year drought’s been severe in eastern and southeast Iowa, but Hillaker says in recent weeks it’s been driest in the southern third of the state. He says since July, southwestern parts of Iowa have had barely a quarter of their normal rain. The northern third of the state, places like Estherville and Spencer, have seen a lot of rain in September, and generally Hillaker says they’ve been wetter than normal for most of the year. Despite the return of warm days, Hillaker says there’s “almost a guarantee” we’ll see frost in the month of October that begins Saturday. Some parts of the state will dodge it, but in western parts of Iowa he says the first frost of winter hits right about now. On average, southeastern Iowa zones will get their first below-freezing temps around October 18. Snow? No. It’s not common. While Hillaker says October gets an average three-tenths of an inch of snow, he explains that means in one year we’ll get a few inches of snowfall, but then won’t see any at all for four or five years. The National Weather Service is offering a map online that shows when various regions of the state get their first frost on the average.
