Based on preliminary data, this April in Illinois is already the 4th wettest on record with 6.58 inches of precipitation. Average statewide precipitation for April is 3.77 inches. So we are already almost two inches above average.
According to the NWS forecast, more rain is expected across southern Illinois on Friday and Saturday. Therefore, it is possible that we will move up the list by the end of the month. In addition, some sites may have already reached their record for April, including the city of Chicago.
Top 5 Wettest Aprils
2011 with 7.40 inches
1957 with 7.13 inches
1927 with 6.95 inches
2013 with 6.58 inches
1944 with 6.50 inches
Precipitation Pattern Across the State
Here is how the precipitation has been distributed around the state, based on our multi-sensor precipitation product, with the actual amounts and the departures from average. Many parts of central and northern Illinois have more than double their average April precipitation (shades of purple in the second map). April precipitation in inches for the first 24 days of the month. Click to enlarge. April precipitation as departures from average. Click to enlarge.
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.
The statewide average temperature for April 2012 was 54.1 degrees, based on available data. The statewide average temperature for March was 55.0 degrees, based on the latest numbers from NOAA. That means that April was almost a degree cooler than March. What makes this even more impressive was that the April temperatures are still 2.4 degrees above normal!
By the way, the statewide normal monthly temperature is 40.7 degrees for March and 51.7 degrees for April, an eleven degree rise.
How rare is it for April to be colder than March? In the statewide records that extend back to 1895, it happened only in 1907 when the March temperature was 47.0 degrees and the April temperature was 43.2 degrees. In all the other cases between 1895 to 2011, April was always warmer.
The highest temperature reported in the state for April was 92 degrees at Kaskaskia on April 2 and at Jacksonville and Pana on April 3. The coldest temperature reported was 23 degrees at Jerseyville on April 17.
Precipitation
The statewide average precipitation was 3.32 inches. That is about 0.5 inches below normal. The rainfall over the weekend was fairly widespread and helped much of the state. In general, the heaviest rains of 5 inches or more fell east of St. Louis. Meanwhile, rainfall amounts of 2 inches or less fell in far southern Illinois, far northwestern Illinois, and a large swath between Peoria and Kankakee. Those areas were 1 to 3 inches below normal for the month (second map).
The highest monthly rainfall total reported in Illinois for April was a CoCoRaHS observer near Belleville (IL-SC-3) with 8.64 inches. Some of the lowest monthly rainfall totals in the state were in Kankakee and Will Counties. For example, Grant Park (IL-KK-19) in Kankakee County reported all 30 days and only received 0.83 inches for the month. April rainfall totals, based on a radar product developed by the National Weather Service. Click to enlarge. April rainfall departure from normal, based on a radar products developed by the National Weather Service. Click to enlarge.
I realized this morning that I was wearing short-sleeve shirts in March and long-sleeve shirts (and a light jacket) in April. It’s like that movie Freaky Friday about the mother and daughter switching bodies, only in this case March and April have switched. [updated April 25] The statewide average temperature for April 1-24 is 53.7 degrees. The statewide average temperature for March was 55.0 degrees, based on the latest numbers from NOAA. That means that April was more than a degree cooler than March. What makes this even more freaky is that the April temperatures are still 2.6 degrees above normal!
BTW, the statewide normal monthly temperature is 40.7 degrees for March and 51.7 degrees for April, an eleven degree rise.
How rare is it for April to be colder than March? In the statewide records that extend back to 1895, it happened only in 1907 when the March temperature was 47.0 degrees and the April temperature was 43.2 degrees. In all the other cases between 1895 to 2011, April was always warmer.
Will this strange situation continue through the end of April? The forecast is for warmer temperatures Wednesday but then a return to cooler conditions afterwards. So we have a good shot at maintaining this record.
