Month: March 2012

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Trouble Ahead from the Warm Weather?

Illinois has just come off its third warmest winter on record. And the warm weather continues in March. The first 7 days have been 3.2 degrees above normal and the NWS forecast for the next 14 days shows high odds of above-normal temperatures.
As a result, plants have begun to think spring is here. On the left are some daffodils in my yard in Champaign today. The blooms are just about to open. It’s the same story for the Magnolia tree at work (picture right). And this is central Illinois. Southern Illinois will be even farther along than here.Photo by Ben Woloszyn.
So what’s the problem? Well, it’s March 8 and we could still have temperatures drop into the 20s in March and April. In fact the median date for the last 28 degree reading in spring in Illinois somewhere near early to mid April in most locations. Our GIS expert Zoe produced this map (left) of the median dates in spring. Click the thumbnail to enlarge.

April Freeze of 2007

An April freeze is exactly what happened in 2007. A warm March was followed by a cold-air outbreak on Easter weekend that caused temperatures to drop into the low 20s and produced high winds.
Below is the plot of the daily average temperature from March 1 to April 30, 2007, for Illinois. There was a small stretch of warm temperatures in early March and then a long stretch in late March and early April with temperatures 10 to 20 degrees above normal. Trees and shrubs rapidly sprouted tender leaves and flowers during this warm spell. Things took a turn for the worst in early April when temperatures plummeted to 10 to 20 degrees below normal for about 2 weeks.
temperature plot for March - April 2007
That particular freeze cause over a billion dollars in damages across the Midwest and Southern U.S. to fruit crops, especially apples and peaches, as well as alfalfa and winter wheat. Here are some reports that outlined the conditions and damages.

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Third Warmest Winter for Illinois

Winter – Temperature

It should be no surprise that this winter was one of the mildest on record for Illinois. “Winter” refers to the three key months of December, January, and February. This year the average winter temperature was 34.2 degrees, 5.2 degrees above normal, and the third warmest winter on record. Here are the top four warmest winters. As you can see, we had a two-way tie for second place.

  • First place, the winter of 1931-32 at 37.1 degrees;
  • Second place, a tie between 1997-98 and 2001-02 at 34.5 degrees;
  • Third place, this winter at 34.2 degrees.

Not only was it warm in terms of the average temperatures, but this winter lacked the really cold weather. Only a few place had temperatures drop below zero. The coldest reading for the winter was a mere -6 degrees at both Galena and Elizabeth in the far northwestern corner of the state.

Winter – Precipitation

The statewide average precipitation for winter was 6.73 inches, just 0.24 inches below normal. Much of that precipitation fell as rain and not snow. Snowfall totals were 50 to 75 percent of normal across much of northern Illinois and 25 to 50 percent of normal in central and southern Illinois. The snowiest spot in the state through the end of February was Woodstock with 27.9 inches, followed closely by Stockton with 27.6 inches and Mt. Carroll with 27.3 inches.

February

The statewide average temperature for February was 35.1 degrees, 4.6 degrees above average. The statewide average precipitation was 1.55 inches, 0.4 inches below normal. Snowfall ranged from less than an inch in southern Illinois to 3 inches in central Illinois. It was a little snowier in the northern third of the state with amounts ranging from 3 to 8 inches.
The statewide records go back to 1895.