History of the Chicago and Rockford Weather Observation Sites

Chicago
Rockford

Weather Observations for the City of Chicago

Official Climate Observation Sites

Location	Occupied From	Occupied To	Remarks
181 W Washington St. (formerly 162 Washington St.)	10/15/1870	10/8/1871	Station abandoned on October 8, 1871 due to the Great Chicago Fire – all records lost.
427 W Randolph St. (10 W Randolph St. prior to 1909)	10/14/1871	6/11/1872	Room rented on October 14. Regular observations resumed on October 16.
20 N Wacker Dr. (80 S Market prior to 1909)	6/11/1872	6/8/1873
Roanoke Building (formerly Major Block) SE corner of Madison St. and LaSalle St.	6/8/1873	1/1/1887
Chicago Opera House SW corner of Clark St. and Washington St.	1/1/1887	2/1/1890
Auditorium Tower NE corner of Wabash Ave. and Ida B. Wells Dr./Congress Pkwy.	2/1/1890	7/1/1905	Automatic recording rain gauge installed in 1897
U.S. Court House 219 S Dearborn St. Photo 1* \| Photo 2*	7/1/1905	12/31/1925	Maintained supplemental observations through October 15, 1970
University of Chicago Rosenwald Hall 58th St. and University Ave. Photo*	1/1/1926	6/30/1942	Maintained supplemental observations through March 31, 1962
Midway International Airport South Terminal Building 6200 S Cicero Ave.	7/1/1942	1/17/1980	Supplemental observations were transferred to station Midway Airport 3SW
O’Hare International Airport International Terminal Building	1/17/1980	3/7/1985
O’Hare International Airport Hardstand Operational Building	3/7/1985	1/19/1989
O’Hare International Airport O’Hare Corporate Tower, Rosemont	1/19/1989	2/1/1996
O’Hare International Airport	2/1/1996	Present	Automated Surface Observing System (ASOS) installed

*Photos provided to the NWS by long time weather observer Frank Wachowski.

Additional Climate Records (but not official for Chicago)

Location	Occupied From	Occupied To	Remarks
U.S. Court House 219 S Dearborn St.	1/1/1926	10/15/1970	Previously was the official observation site for Chicago. Observations continued local site’s climate record.
University of Chicago Rosenwald Hall 58th St. and University Ave.	1/1/1916 and 7/1/1942	12/31/1925 and 3/31/1962	Temporarily was the official observation site for Chicago. Observations continued local site’s climate record.
University of Chicago 5730 S Woodlawn Ave.	4/1/1962	10/31/1994	Previously was the official observation site for Chicago. Observations continued local site’s climate record.
Midway International Airport National Airtransport Hangar 5490 S Cicero Ave.	2/13/1928	11/3/1932
Midway International Airport South Terminal Building 6200 S Cicero Ave.	11/3/1932	6/30/1942	Continuation of MDW climate records. Became the official observation site for Chicago on 7/1/1942.
Midway Airport 3SW (Cooperative Observer)	1/18/1980	Present	Continuation of MDW climate records after the official observation site for Chicago was transferred to O’Hare
Midway International Airport	5/1/1997	Present	Regular observations resumed at Midway Airport after an Automated Surface Observing System (ASOS) was installed
O’Hare International Airport International Terminal Building	10/30/1958	1/16/1980	Beginning of ORD climate records. Became the official observation site for Chicago on 1/17/1980.

Weather Observations for the City of Rockford

Official Climate Observation Sites

Location	Occupied From	Occupied To	Remarks
900 Block, N Main St.	12/??/1872	10/??/1893	Cooperative observer, T. D. Robertson (rainfall only)
731 N Court St.	11/??/1893	12/??/1912	Cooperative observer, H. C. Porter (rainfall only)
1135 N Court St.	1/??/1913	6/1/1918	Cooperative observer, Dr. John R. Porter (temperature observations added)
731 N Court St.	6/2/1918	7/29/1920	Cooperative observer, Carson H. Porter
324 Churchill St.	7/30/1920	12/19/1950	Cooperative observers, F. W. Knowlton and Daughter
Rockford Airport Federal Facilities Building	12/19/1950	7/1/1995
Rockford International Airport	7/1/1995	Present	Automated Surface Observing System (ASOS) installed

Additional Climate Records (but not official for Rockford)

Location	Occupied From	Occupied To	Remarks
324 Churchill St.	12/19/1950	9/23/1953	Cooperative observers. Previously was the official observation site for Rockford.
2221 North Winnebago St.	9/24/1953	6/30/1957	Continuation of the same cooperative observer's climate record at a new residence.