NORMAL

JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC

Day of Month	High	Low	Average	HDD	CDD	Precipitation	Snowfall
1	32	17	24	41	0	0.06	0.3
2	31	17	24	41	0	0.07	0.3
3	31	17	24	41	0	0.06	0.4
4	31	17	24	41	0	0.06	0.3
5	31	17	24	41	0	0.06	0.3
6	31	17	24	41	0	0.07	0.3
7	31	17	24	41	0	0.06	0.4
8	31	17	24	41	0	0.06	0.3
9	31	17	24	41	0	0.06	0.4
10	31	17	24	41	0	0.06	0.3
11	31	16	24	41	0	0.06	0.3
12	31	16	24	41	0	0.06	0.4
13	31	16	24	41	0	0.05	0.3
14	31	16	24	41	0	0.06	0.4
15	31	16	24	42	0	0.06	0.3
16	31	16	24	42	0	0.05	0.3
17	31	16	23	42	0	0.06	0.4
18	31	16	23	42	0	0.05	0.4
19	31	16	23	42	0	0.05	0.4
20	31	16	23	42	0	0.06	0.3
21	31	16	24	42	0	0.05	0.4
22	31	16	24	42	0	0.05	0.4
23	31	16	24	41	0	0.05	0.3
24	31	16	24	41	0	0.06	0.4
25	31	16	24	41	0	0.04	0.3
26	31	16	24	41	0	0.05	0.4
27	31	16	24	41	0	0.05	0.3
28	31	17	24	41	0	0.05	0.4
29	31	17	24	41	0	0.05	0.3
30	32	17	24	41	0	0.05	0.4
31	32	17	24	41	0	0.05	0.4
MONTH	31.0	16.5	23.8	1279	0	1.73	10.8

HDD = A Heating Degree Day represents the number of degree(s) that the mean temperature for the day is below 65 degrees during a day.

CDD = A Cooling Degree Day represents the number of degree(s) that the mean temperature for the day is above 65 degrees during a day.

SOURCE: NWS Chicago Normals (1981-2010) January ...
Normals for Chicago for Temperature, Precipitation and Snowfall (by month)

January Notes
Snow! Greatest potential for snow (as much as 20 inches can fall in a little more than 24 hours and greatest potential for the lowest temperatures of the year and all-time record lows. Snow cover can stay around for the entire month. Fog possible if a warm day occurs with snow on the ground. Days start getting longer around January 5, but nobody notices.

January 11-27 the normal low in Chicago hits and maintains the year's lowest normal temperature of 16 F. Mid-January is the coldest part of the winter in Chicago. Record highs in January are in the 50's and 60's F. Record low ranges -9 to -27 F.

CHICAGO O'HARE CURRENT AND HISTORY (3-DAY) ... | NWS Chicago Office OBSERVED WEATHER REPORTS

HOMETOWN WEATHER: Arlington Heights Weather Forecast -- Arlingtoncardinal.com/weather

LIVE RADAR | STORM TRACKS | CLOUDS INFRARED SAT | CLOUDS VISIBLE SAT (during daylight)

WunderMap® with Temperature/Wind Data || Google: O'Hare  Temps | NE Illinois Temps
Full Screen Motion Weather Radar (Wunderground.com) Midwest Cloud Cover and Arlington Heights Weather Forecast

SUNLIGHT DATA FOR SECURITY, TRAFFIC SAFETY, AND SPORTS
SunCalc.net data with azimuth & trajectory, times for dawn, sunrise, solar noon, sunset, dusk ...