Does Our Warm March Weather Mean We Will Have a Hot Summer?

Northern Illinois and northwest Indiana are in the midst of a rare March warm spell. For the first half of the month of March, Chicago was 11.9 degrees above normal and Rockford was running 10.6 degrees above normal. What does that mean for the rest of this spring and summer? Here is a look back at other warm Marches and how the following springs and summers turned out.
Chicago
March rank
Year
Avg Temp
Departure
from Normal (37.9)
Spring Avg
Departure from normal (47.7)
Summer Avg
Departure from normal (71.8)
No. of 90 degree days
1
1945
48.6
+10.7
50.8
+3.1
69.8
-2.0
16
1
1910
48.6
+10.7
51.1
+3.4
72.5
+0.7
9
3
1946
47.2
+9.3
51.7
+4.0
71.0
-0.8
21
4
1921
45.8
+7.9
53.9
+6.2
75.9
+4.1
23
5
1878
45.3
+7.4
51.0
+3.3
71.6
-0.2
4
6
1973
45.1
+7.2
49.8
+2.1
75.3
+3.5
29
6
1938
45.1
+7.2
51.2
+3.5
72.1
+0.3
9

From this table we can see that years with very warm Marches ended up having very warm springs. The spring of 1921 was the second warmest on record. In fact all but 1973 ranked in the top 20 all time. But a similar correlation with warm summers does not exist. Three of the summers following a warm March were above normal and only 2 were much above normal. Summer of 1921 was the 3rd warmest on record. But 2 of the summers were near normal and 2 were below normal. We can also look at the number of days of 90 degree weather. Three of the years had an excessive number of 90 degree days, 3 had less than the normal number of 90 degree days, and one was close to normal.

Here is a look at month by month averages for April and May following a warm March 

March rank
Year
Avg Temp
Departure
from Normal (37.9)
April Avg
Departure from Normal (48.9)
May Avg
Departure from Normal (59.1)
1
1945
48.6
+10.7
49.8
+0.9
54.1
-5.0
1
1910
48.6
+10.7
51.2
+2.3
53.5
-5.6
3
1946
47.2
+9.3
51.1
+2.2
56.9
-2.2
4
1921
45.8
+7.9
54.2
+5.3
61.7
+2.6
5
1878
45.3
+7.4
52.5
+3.6
55.3
-3.8
6
1973
45.1
+7.2
48.6
-0.3
55.7
-3.4
6
1938
45.1
+7.2
50.3
+1.4
58.3
-0.8

 
Six of the 7 Aprils following a warm March were also above normal, but 6 of the 7 following Mays were cooler than normal, and in 4 of the years May was much cooler than normal.
 
Rockford
 
March rank
Year
Avg Temp
Departure
from Normal (36.1)
Spring Avg
Departure from normal (47.7)
Summer Avg
Departure from normal (71.8)
No. of 90 degree days
1
1945
48.2
+12.1
50.7
+3.0
69.9
-1.9
19
2
1910
45.1
+9.0
49.9
+2.2
72.0
+0.2
26
3
1946
44.9
+8.8
M
NA
M
NA
M
4
1938
44.0
+7.9
51.6
+3.9
72.4
+0.6
19
5
2000
43.0
+6.9
50.7
+3.0
69.8
-2.0
4
5
1973
43.0
+6.9
48.8
+4.7
72.4
+0.6
13
7
1921
42.7
+6.6
53.2
+5.5
76.1
+4.3
62
 

Similarly, springs with warm Marches ended up above normal in Rockford but the results for the following summers were inconclusive. 1921 was the second warmest spring on record and the warmest summer ever in Rockford. There is missing data from the spring and summer of 1946.

Here is a look at month by month averages for April and May following a warm March 

March rank
Year
Avg Temp
Departure
from Normal (37.9)
April Avg
Departure from Normal (47.9)
May Avg
Departure from Normal (59.6)
1
1945
48.2
+12.1
49.8
+1.9
54.1
-5.5
2
1910
45.1
+9.0
50.3
+2.4
54.4
-5.2
3
1946
44.9
+8.8
M
NA
M
NA
4
1938
44.0
+7.9
50.4
+2.5
60.4
+0.8
5
2000
43.0
+6.9
47.7
-0.2
61.5
+1.9
5
1973
43.0
+6.9
47.6
-0.3
55.8
-3.8
7
1921
42.7
+6.6
53.6
+5.7
63.3
+3.7

 
Most of the Aprils following a very warm March continued above normal and 2 were near normal. The Mays following a warm March were split between warmer or cooler than normal, but the Mays following the 2 warmest Marches were much below normal.


Return to News Archive

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.