Cook County Precipitation NetworkNancy Westcott
The Cook County Precipitation Network is a 25-site weighing-bucket raingage array operated year-round by the Illinois State Water Survey for the U.S. Army Corps of Engineers and the U.S. Geological Survey since 1989. The network is located in the Lake Michigan and Des Plaines River watersheds of Cook County to provide accurate precipitation measurements for modeling storm runoff, a crucial parameter used in the computation of the amount of water diverted from Lake Michigan into Illinois waterways. The map at right shows the approximate locations of the raingages.
Archived daily data are available for previous water years from the Cook County Precipitation Network Data Archive, archived quality-controlled hourly (all years) or 10-minute (recent years) data are available through the Midwestern Regional Climate Center. Preliminary real-time 10-minute and hourly data are available from the Cook County Precipitation Network Data Collection page. The data are quality controlled during the first week of each month and are reviewed again in October after completion of the Water Year.