It’s no secret that Chicago had a mild winter, but now the data is in.
The period from Dec. 1 to the end of February was the city’s fourth warmest in the last 70 years and the 14th warmest since records began in 1872, according to Illinois state climatologist Trent Ford.
“It’s pretty rare, and we’re seeing the effect of that,” Ford said. “All across the state, people are reporting an early break to spring. The big question is, now that we’ve moved into a cooler pattern, what kind of damage (will we) see to those early spring perennials?”
Spring growth is about two or three weeks ahead of where it would normally be this time of year, leaving buds and blossoms vulnerable to freezing. Among the plants that could be affected are tulips, daffodils, elderberry bushes and fruit-bearing trees, such as peach and apple.
Ford said a relatively balmy average winter temperature of 31.8 degrees at O’Hare International Airport was due in part to climate change, but naturally occurring weather patterns played a part as well.
“(Warm weather) in any given month, season or year is never just because of climate change,” said Ford, who pointed out that some of the city’s warmest winters were in the late 19th century.
Human-induced climate change boosts the effects of natural weather patterns associated with warm winters, he said.
Winter is the fastest warming season in most of the United States, according to Climate Central. Average winter temperatures across the lower 48 states have increased by nearly 3 degrees since 1896, according to the Environmental Protection Agency.
In Chicago, the winters of 2011-12, 2001-02 and 1997-98 were all warmer than this one.
In Chicagoland, the response to warm weather has included February snowdrop displays and the current buds on daffodils.
Unfortunately, the early growth leaves plants more vulnerable to spring freezes. Tulip blooms that might last for two weeks can be destroyed in a day. Trees may not flower, and in turn won’t bear fruit, depriving animals of food.
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The nursery industry and the peach growers of southern Illinois can suffer as well.
Chicago is currently about two to three weeks away from its average last spring freeze. In the northwest suburbs, there’s often a freeze in the third or fourth week of April, Ford said.
Ford, who lives in Champaign, is concerned about his own elderberry bushes, which endured two subfreezing nights this past weekend: “I don’t think I will have flowers.”
Around the state, apple trees appear to be holding up, he said, with buds tight enough to stand the cold, but the peach orchards of southern Illinois are a question mark. It’s still a little too soon after last weekend’s cold snap to judge the effects, he said.
As for the likelihood of the traditional April snow in Chicago, Ford laughed: “I don’t want to go on the record.” He noted a recent National Weather Service forecast that leans toward a warm April but said that’s not a guarantee.
“It’s April in Chicago. We’re not going to rule out a stray snow shower,” Ford said.
