CHICAGO MIDWAY AP 3 SW, ILLINOIS

Period of Record General Climate Summary - Heating Degree Days

Station:(111577) CHICAGO MIDWAY AP 3 SW
From Year=1928 To Year=2012
Heating Degree Days for Selected Base Temperature (F)
Base	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Annual
65	1259	1047	839	472	208	37	2	5	79	338	725	1117	6129
60	1104	906	688	339	114	11	0	0	29	216	578	962	4947
57	1011	821	598	266	72	4	0	0	13	155	492	870	4303
55	949	765	540	221	51	2	0	0	7	120	437	808	3900
50	795	625	401	126	17	0	0	0	1	54	307	655	2980

Heating Degree Day units are computed as the difference between the base temperature and the daily average temperature. (Base Temp. - Daily Ave. Temp.) One unit is accumulated for each degree Fahrenheit the average temperature is below the base temperature. Negative numbers are discarded. Example: If the days high temperature was 65 and the low temperature was 31, the base 50 heating degree day units is 50 - ((65 + 31) / 2) = 2. This is done for each day of the month and summed.
Table updated on Oct 31, 2012
Months with 5 or more missing days are not considered
Years with 1 or more missing months are not considered

Western Regional Climate Center, wrcc@dri.edu