Over 8,700 volunteers from the fifty states and all territories report at least daily a variety of weather conditions such as daily maximum and minimum temperatures, 24-hour precipitation totals, including snowfall, and significant weather occurrences throughout a day that are recorded via remarks in observer logs.

Observation locations include farms, in urban and suburban areas, National Parks, seashores, and mountaintops.

Volunteers are trained by local NWS offices who provide rain gauges, snowsticks, thermometers, or other instruments.

[2] The program began with act of Congress in 1890[1] and grew out a network of observers developed by the Smithsonian Institution.

The coop network predates but grew to supplement significant surface weather observation sites typically located around major airports.