Second Coldest April on Record in Illinois

Based on the official data, the statewide average temperature was  44.5 degrees,  8.1 degrees below normal. It was the second coldest April on record, only beaten by 43.1 degrees set in April 1907. Our statewide records go back to 1895. Normal refers to a specific benchmark, the 1981-2010 average. See the longer explanation here.
Here are the temperature departures from normal look like across the Midwest. Areas in green are 1 to 9 degrees below normal, while areas in icy blue are 9 or more degrees below normal. The lowest temperature reported in Illinois for April was -1 at both Avon and Lincoln on April 2. At the other extreme, we did reach into the 80s at times during the month. The warmest reading was 86 degrees at Kaskaskia on April 13.
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Latest News – 6th Coldest Year on Record for Illlinois

The National Climatic Data Center (NCDC) released their numbers for 2014 and Illinois ended up at 49.5 degrees and the 6th coldest year on record for Illinois. Other Midwestern and southern states experienced one of the 10 coldest years for their particular state. Meanwhile,  many of the western states experienced one of their warmest years on record. In fact, the two extremes cancelled out leaving the US ranked as the 34th warmest on record.

This result differs from an earlier post where I calculated the 2014 temperature at 49.4 degrees (0.1 degrees colder) based on available data right at the start of the new year. This new calculation moved us from 4th to 6th place in the list. I normally defer to the NCDC numbers and rankings as the final answer on the subject. However, it’s important to keep in mind that their numbers are preliminary as well so the final number and ranking may not be settled for another month or two as more data arrives and is processed.


Cold Start to November in the Midwest

So far, November has been cooler than average across Illinois and the eastern two-thirds of the Midwest (below). The statewide average temperature is about 5 degrees below average.

The NWS forecasts indicate that temperatures are likely to stay below-average for the next two weeks across Illinois and the Midwest. The second and third maps are the latest NWS 6-10 and 8-14 day forecasts.


Ten Coldest March's and What Follows

As previously reported, based on preliminary data this March in Illinois was 34.1 degrees and the 11th coldest March on record. What were the ten coldest March’s on record? I have listed them in the table below. Also I looked to see what happened in April after these chilly March’s. It turns out that half are above average and half are below average – a virtual coin toss.
The columns labeled “Depart” are the departures from the 1981-2010 statewide averages. Probably the biggest turnaround was between March 1960, which was the coldest March on record and 15.5 degrees below average, compared to April 1960 which was 2.2 degrees above average. The statewide temperature records go back to 1895. 

Rank Year March Depart April Depart
1 1960 25.6 -15.5 54.6 2.2
2 1906 30.3 -10.8 54.5 2.1
3 1912 30.4 -10.7 52.6 0.2
4 1965 31.1 -10.0 52.9 0.5
5 1984 33.0 -8.1 49.8 -2.6
6 1932 33.2 -7.9 52.1 -0.3
7 1978 33.5 -7.6 52.5 0.1
8 1989 33.5 -7.6 51.1 -1.3
9 1947 33.8 -7.3 51.0 -1.4
10 1926 34.0 -7.1 45.4 -7.0
11 2013 34.1 -7.0 ?? ??

BTW, so far this April has been cool. The first 7 days averaged 44.4 degrees statewide, and about 3 degrees below average.

March – Much Colder Than Last Year

The preliminary numbers are in – the statewide temperature for March of this year was 34.1 degrees. That is 7 degrees below the long-term average of 41.1 degrees and the 11th coldest March on record. That is in remarkable contrast to March 2012, which ended up at 55.3 degrees. That March was 14.2 degrees above the long-term average and the warmest March on record. In fact, the difference between this March and last March was a whopping 21.2 degrees.
The statewide precipitation was 2.85 inches, which is 0.15 inches below the long-term average of 3.00 inches. Precipitation amounts were largest just east of St. Louis and lightest in east-central Illinois. The largest monthly total came from Kaskaskia with 6.42 inches of precipitation. Several surrounding sites had in excess of 5 inches.
[updated 4/11/13] Snowfall was above-average for the month thanks mostly to a large storm that passed through central Illinois on March 24-25 and some earlier events that passed through northern and western Illinois. The Springfield COOP site received 17 inches in 24 hours, a new 24-hour record for that site, and a storm total of 18.5 inches. They finished the month with 19.6 inches of snow. The CoCoRaHS site at Nokomis (IL-MY-1), to the south of Springfield, had a similar experience with 19 inches of snow from the one storm and a monthly total that tied Springfield with 19.6 inches. A CoCoRaHS site at Springfield (IL-SG-17) reported 18 inches during the one storm and a monthly total of 19.5 inches.
Precipitation totals and departures from the long-term average for March:

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Snowfall totals and departures from the long-term average for March:
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January Climate Stats

The average statewide temperature for January in Illinois was 21.8 degrees, 3 degrees below normal. That’s warmer than last January when the statewide temperature was only 20.3 degrees and a far cry from the record low January of 1977 when the average temperature was only 10.3 degrees.
The warmest temperature of the month was in Cairo with 67 degrees on January 1. The coldest temperature of the month was in Mt. Carroll with -20 degrees on January 21.
Snowfall was close to normal across much of the state. Amounts ranged from 4 inches in far southern Illinois to over 12 inches in parts of western and northeastern Illinois. Spring Grove, along the Illinois-Wisconsin border, reported the largest snowfall  amount in the state with 15.1 inches.
While snowfall was close to normal in most areas, the statewide precipitation (rainfall + water content of snow) was only 1.23 inches, 0.7 inches below normal. Olney reported the largest monthly precipitation amount in the state with 2.81 inches.
Update: added maps for January snowfall, precipitation and temperature departures on February 4.

January 2011 snowfall for Illinois.
January 2011 snowfall for Illinois.

January 2011 precipitation for Illinois.
January 2011 precipitation (rainfall + water content of snow and ice) for Illinois.

January 2011 temperature departure for Illinois.
January 2011 temperature departures from normal for Illinois.


First Half of January – Slightly Colder than Normal

The Illinois statewide average temperature for January 1-15, 2010, was 21.5 degrees, 2.3 degrees below normal. The statewide average precipitation for the same period was 0.75 inches, 84 percent of normal. Precipitation includes both rainfall and the water content of any snowfall.
After a very active December in terms of snowfall, January has been relatively quiet so far. The only significant snowfall totals are in western Illinois and along Lake Michigan. However, the persistently cold weather means the snow has stuck around.

Snowfall for January 1-15, 2010, in Illinois.

December 2010 in Illinois – Cold and Snowy

December 2010 in Illinois turned out to be one of the coldest and snowiest on record. I updated the numbers on January 3 and the maps on January 5.


The average statewide temperature was 24.0 degrees, 5.8 degrees below normal and the 12th coldest on record, based on preliminary data.


Snowfall was above-normal throughout the state in December and heaviest in a band from northwest Illinois into east-central Illinois (see maps below). Snowfall totals for December include 20.4 inches in Champaign-Urbana (snowiest December on record), 18.1 inches in Bloomington-Normal(second snowiest December on record), and 19.2 inches in Peoria (third snowiest December on record). Champaign-Urbana beat both Rockford (19.2 inches) and Chicago O’Hare Airport (16.2 inches) on snowfall totals. The largest snowfall total reported in the state was 30.0 inches near Galena by a CoCoRaHS observer. Streator reported 28.5 inches, the highest amount from a NWS cooperative observer.


Even though snowfall was above average in most locations, the average statewide precipitation was 1.8 inches, 0.9 inch below normal. Some of the snowfall did not have a high water content, especially if it fell when the temperatures were in the 20s. While the rule of thumb is that 10 inches of snow equals 1 inch of water, a  10 to 1 ratio, I have seen ratios ranging from 4 to 1 to 22 to 1 in Illinois.

December 2010 snowfall
The December 2010 total snowfall in inches.

December 2010 snowfall departure in Illinois
The December 2010 snowfall departures (inches) in Illinois.


Update on Cold Weather in Illinois

As of December 21, Illinois remains 10.2 degrees below normal for the month. At 20.9 degrees, this is now the 5th coldest December since statewide records began in 1895. It could still move up or down in the ranking, depending on how the rest of December behaves.
Statewide precipitation stands at 1.06 inches of precipitation (rainfall plus the water equivalent of any snow).
Snowfall totals for the month ranges from less than 2 inches in far southern Illinois to over 14 inches in northwest Illinois (see map below). Right now the two spots with the most snowfall in the state for December are a CoCoRaHS site near Marseilles with 18.5 inches and a CoCoRaHS site near Champaign with 18.3 inches of snow.
From my web page on current conditions in Illinois, here is the breakdown by region within the state as well as the statewide numbers at the bottom for December 1-21.

                        12/01/2010 to 12/21/2010
Climate          <------Temperature----->   <---------Precipitation--------->
Division         Actual   Normal      Dev   Actual   Normal     Dev   Percent
Northwest          15.2     26.3    -11.0     1.44     1.45    -0.01       99
Northeast          17.0     27.9    -10.9     1.30     1.63    -0.33       80
West               21.4     29.7     -8.3     0.56     1.63    -1.07       34
Central            18.9     29.7    -10.8     1.13     1.76    -0.63       64
East               17.6     30.1    -12.4     1.53     1.75    -0.23       87
West-southwest     23.8     32.5     -8.6     0.56     1.91    -1.35       29
East-southeast     23.3     33.6    -10.2     1.23     2.04    -0.80       61
Southwest          26.2     35.7     -9.5     0.79     2.31    -1.52       34
Southeast          26.4     36.4    -10.0     0.93     2.43    -1.50       38
State              20.9     31.1    -10.2     1.06     1.86    -0.79       57
Dev means Deviation From Normal, Percent means Percent of Normal
December snowfall in Illinois
Snowfall for Illinois for December 1-21, 2010.

Cold Start to December

After such nice weather in October and most of November, real winter weather arrived in Illinois for December. The statewide average temperature for the first 14 days of December was 22.0 degrees, 10.6 degrees below normal.
The statewide average precipitation is 0.83 inches, 0.5 inches below normal.
Snowfall has been widespread across the state in early December. Snowfall totals range from less than an inch in far southern Illinois to over 10 inches in northwestern Illinois. See map below for snowfall totals for December 1-14, 2010.

December 1-14, 2010 snowfall.
Snowfall for December 1-14, 2010, for Illinois.