Dec 13, 2021 - News

December heat wave forecast for Iowa may impact farming

Number of winter days above normal in Des Moines per year
Data: Climate Central; Chart: Jared Whalen/Axios

Your eyes aren't deceiving you — Iowa's December temperatures are set to spike into jaw-dropping numbers this week, potentially breaking into the 70s on Wednesday.

Driving the news: A December heat wave is set to blanket much of the contiguous U.S. over the next two weeks, writes Axios' Andrew Freedman.

  • The jet stream is poised to dive south toward the western U.S., bringing much-needed rains and mountain snows to a parched California and other western states.
  • But to the east of this jet stream dip, a potentially record strong ridge of high pressure is projected to set up over the Central U.S., resulting in the heat.

What it means for us: For most Des Moines residents, this week is a great time to play hooky and go outside.

  • But for our farmers, the mild fall and the unusually warm winter temperatures bring their own difficult balance.

Details: Farmers have a wider window to finish fieldwork and grow more long-season crops before the soil freezes.

  • Yes, but: A shorter freeze means they may face a higher pest population in 2022 than if they died out over the winter time, said Meaghan Anderson, a field agronomist at Iowa State.

The big picture: There is climate change context to this heat wave. Winter is the most rapidly warming season in the U.S. (meteorologists define winter as the months of December, January and February).

  • In Des Moines, for example, the average winter temperature has increased by 4.5°F since 1970, with 11 more days with highs above a particular threshold, according to data from the climate research organization Climate Central.

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