Iowans are well aware that 2018 is starting out much colder than normal, with wind chills of 30-below and worse, but the final tallies on the last month of 2017 show a wide range of temperatures. State climatologist Harry Hillaker says December covered both extremes, starting out very mild. Hillaker says, “We had a few 70-degree readings early on and then a very, very cold last week or so of the month with the coldest weather coming on New Year’s Eve when it got down to 22-below zero at the Spencer airport.”

That ended up being the lowest temperature anywhere in the state for the calendar year. Here in Atlantic, the temperature at the KJAN Studios got down to -26 on Dec. 31st. That was the coldest day of the month and for the year. It was also a record Low for that date. December concluded just one-half of one-degree warmer than normal statewide, but in Atlantic, it was 3.1 degrees warmer than normal. A dry spell started in late October, carried through all of November, and continued well into December, until the snow began to fall.

“Roughly the last ten days or so in December, snowfall started to become more common,” Hillaker says. “It was about an every-other-day occurrance, at least some light snow in some parts of the state. It still didn’t amount to much as far as overall moisture. Statewide average, we had just 42/100ths of precipitation for the month.” That’s less than the norm and it ended up being Iowa’s 12th driest December in 145 years of records. In Atlantic, we received a total of 5.1 inches of snow, worth a little more than one-third of an inch (.36″) liquid value.

Snowfall statewide averaged 5.8 inches during the month, which was close to average. January is opening up very frigid and the forecast calls for a colder-than-normal month ahead. “It’s a very cold start to the month,” he says. “It’ll take quite a warm-up at some point in the month to get us back above normal.”  We recorded a record High in December of 64 on the 3rd.  on the More moderate temperatures may arrive by this weekend with slightly-above normal temps possible, though Hillaker says we’ll likely be back down into the very cold weather by next week. Precipitation for January, he says, will likely be below normal. In Atlantic, normal precip. for the month is .84″.  The average High is 29, and the average Low is 9.

(Radio Iowa/KJAN Weather records)

The weather pattern known as La Nina may get part of the blame for this bout of exceptionally cold weather. Observers are becoming more concerned with the current La Nina strengthening and what that could mean months from now. Doug Kluck, the climate services director for the National Oceanic and Atmospheric Administration in Kansas City, says they’re carefully watching precipitation trends. Kluck says, “It’s going to be an interesting winter and early spring to see if and when precipitation materializes and how much.”

A La Nina pattern occurs when Pacific Ocean surface temperatures drop below long-term normals. It can impact the climate across North America, bringing some areas more storms, and droughts elsewhere. Kluck says they’ve seen similar trends with past La Ninas. “It is sort of a worrisome pattern that we’ve been in up to this point,” Kluck says. “We’ve seen these dry and warm falls switch into or become dry springs and summers the next year, especially after a second La Nina and this is two years in a row.”

He notes there was a similar pattern in 2012, which resulted in a long drought for much of the Midwest and Northern Plains.

(Radio Iowa, w/thanks to Jerry Oster, WNAX, Yankton)