CEDAR RAPIDS — Iowans who went south for late winter comfort missed the second warmest February on record — a month notable for such anomalies as surging maple sap, blooming crocuses, surfacing nightcrawlers and the early birds that dote on them.
This February was the second warmest in 145 years, with a statewide average temperature of 34 degrees, which is 10 degrees warmer than the normal 24 degrees, said State Climatologist Harry Hillaker.
That warmth tricked maple trees into circulating their sap much earlier than usual, said John Myers, executive director at Indian Creek Nature Center in Cedar Rapids.
“Sap normally doesn’t flow until March, but we collected 900 gallons in the last two and a half weeks of February. That’s more than we collected all last year,” Myers said.
Noting that sap stops flowing when nighttime temperatures remain above freezing, Myers said collections halted for a few days early last week but have since resumed, ensuring the nature center will have ample syrup on hand for its annual festival on March 18 and 19.
Iowa’s recently concluded meteorological winter — December through February — was the ninth warmest in 144 years of record-keeping in that category, its statewide average temperature of 26.9 degrees exceeding the 22.1-degree normal by 4.8 degrees.
The prematurely flowing sap was just one of many signs of the early-departing winter.
Mike Jacobs of Monticello reported seeing his first red-winged blackbird, a reliable harbinger of spring, on Feb. 19, about three weeks ahead of their typical arrival date.
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Following a warm rain on Feb. 20, nightcrawlers climbed through frost-free soil and glistened in the glow of a flashlight in a Buchanan County yard. Eight days later, a crocus bloomed in that same yard.
Hillaker said five of the 10 warmest winters in 144 years have occurred in the past 20 years.
University of Iowa engineering professor Jerry Schnoor, co-director of the Center for Global and Regional Environmental Research, said the recent spate of warm Iowa winters is consistent with climate science models and projections.
Noting that all the planet’s 10 warmest years have occurred since 1998, Schnoor said “Iowa winters are consistent with global patterns, if somewhat less extreme.”
Warmer winters and warmer nights, along with higher humidity, more rain and more extreme rainfall events, are among the most noticeable effects of climate change in Iowa, according to Iowa State University climate scientist Gene Takle.
Myers expressed concern that the trend toward warmer winters and earlier springs could threaten the nature center’s maple sap harvest.
“We’re right on the southwestern edge of the maple syrup zone, and we could be pushed out of it if the climate shifts and stays that way,” he said.
This past winter was the 25th wettest in 144 years with a statewide average of 4.26 inches of precipitation, 0.92 inches above normal.
Because of the unusual warmth, however, a larger than normal percentage of precipitation fell as rain rather than snow.
With a statewide average of 17.1 inches of snow — 8.8 inches less than the normal 25.9 inches — the recently concluded winter ranks as the 29th least snowy in 130 years.
Locally, Cedar Rapids established a new all-time February high temperature of 76 degrees on Feb. 22. It was one of four days with high readings in the 70s during February, a month that also had five days with highs in the 60s and seven days with highs in the 50s, according to the National Weather Service.
Cedar Rapids’ average high for the month was 46.5 degrees, 13.2 degrees warmer than normal.
Here is a look at the average temperature from December through February during the 10 warmest winters in Iowa over the past 144 years. The average statewide temperature during those three months is 22.1 degrees. Five of the 10 warmest winters have been in the past 20 years.
1. 1877-78 — 30.3 degrees
2. 2001-02 — 29.0
3. 1930-31 — 28.4
4. 1981-82 — 28.3
1991-92 — 28.3
6. 1997-98 — 27.9
7. 2011-12 — 27.8
8. 1986-87 — 27.5
9. 2016-17 — 26.9
10. 2015-16 — 26.7
Source: Harry Hillaker, Iowa state climatologist