Don’t let an early fall freeze ruin your year
On Aug. 27, 2013, temperatures blistered the ground around Des Moines, Iowa, at a near-record 102°F. In fact, the late August heat wave pushed temperatures into the upper 90s or higher around much of the Midwest. Corn leaves curled up and farmers wiped the sweat from their brows.
Yet the No. 1 concern on many minds was how early the first killing frost would arrive.
Crop market strategist Ted Seifried says the cooler, wetter spring made this conversation inevitable—late summer heat wave or not.
"A cold and wet spring did two things," he says. "One, it recharged subsoil moisture levels in most areas after a severe drought last year. Two, it caused massive planting delays. So, it was a bit of a bittersweet spring."
Timing is everything, and it has generally not been on agriculture’s side in 2013. A late-planted spring is not a recipe for disaster by itself, but throw in a cooler-than-normal May, June and July and chase it with the aforementioned August heat wave, and suddenly a little concern just might be justified. Fortunately, the Southern Corn Belt already has harvest put to bed by October, but much of the upper Midwest, from the Dakotas to Michigan, will be watching the thermometer.
The trouble with predicting early frost is that it’s not reliable to do so until about 10 to 14 days out, explains Laura Edwards, an Extension climate field specialist with South Dakota State University.
For example, although a hot spell in August will build much-needed growing degree units (GDUs), it’s not an accurate predictor of a late frost, Edwards says. The opposite is also true, she says—a cool August doesn’t correlate to an early frost, either.
"From year to year, it really varies quite a bit," she says.
When the first frost will land is anybody’s guess, but Edwards feels sympathetic for farmers in the upper Midwest who need that date to come as late as possible.
"We’re all crossing our fingers for an average or late freeze date," she says.
Early fall freeze is one of six climatic calamities covered by Total Weather Insurance (TWI) policies for corn available from The Climate Corporation. The company’s corn TWI policies issue payouts to policyholders based on any GDU shortfalls that exist when the first killing freeze of the fall occurs.
This shortfall is calculated by looking at planting date, relative maturity and to-date GDU accumulation, says director of agronomic research Jeff Hamlin. Using this and other data, Climate Corp has created a unique look at fall freeze risk with a map that shows this risk to corn in each part of the Corn Belt, he says.
"This resource is going to help answer the big question right now—is the crop going to get to black layer before the first killing freeze," he says.
The freeze risk map is updated at insights.climate.com every few days with additional forecast information.
- October 2013