The calendar change to September gets some people thinking about the onset of fall and the first frost. State Climatologist, Harry Hillaker, says frost would normally not be a concern until the end of this month.He says the first frost usually doesn’t hit until the last week of September in northern Iowa.
“But that does vary tremendously from one year to the next..in fact just last year would have been one of those cases where we had pretty widespread frost even in the middle of September down into central Iowa. So, it’s one of those things that you just never know,” Hillaker says.
The dry conditions the state has experienced lately could be a signal of an early frost. “For much of this July and August humidity is much lower than usual. Dry air cools much more rapidly than moist air does,” Hillaker explains. “So it somewhat increases the odds for getting and early frost because that very dry air could cool off very rapidly at night.”
The good news is the growing season is ahead of schedule and that means an early frost likely wouldn’t be a problem for crops. “Unless something really drastic were to happen quite soon, certainly corn in many cases is already mature. And in case where it isn’t mature it certainly will be mature before very long. And even with soybeans, that crop will be mature before much longer as well. So the chances of frost causing significant problems (is) pretty small,” according to Hillaker.
Hillaker says the impact of the dry air was evident earlier this year when temperatures dropped into the 30s.