History

Staff at the McCormick Observatory have been recording daily weather measurements and sending them to the National Weather Service since 1894. Temperature, precipitation, and sky conditions are all measured, observed, and recorded. Data was originally sent by mail, then sent by telegram. Today, the data is sent online. 

The NWS then merges that information with data from about 11,000 other sites around the country to create a big-picture view of the nation's climate. Over the span of time, years and decades and, ultimately, centuries, clear patterns emerge, indicating warming or cooling trends and seasonal averages.

Dozens of leather-bound ledgers are stored at the Observatory, each containing hundreds of entries, written and signed in fountain pen ink by long-gone observers.

Modern Observations

The Observatory's weather observations is part of the National Weather Service's Cooperative Observer Program (COOP). In this program, more than 10,000 volunteers take daily weather observations at National Parks, seashores, mountaintops, and farms as well as in urban and suburban areas. COOP data usually consist of daily maximum and minimum temperatures, snowfall, and 24-hour precipitation totals. These data may include additional hydrological or meteorological data such as evaporation or soil temperatures. Online data access is provided at no charge.

McCormick Observatory's COOP station is Charlottesville 2W COOP Station. You can explore historical weather data by visiting the Iowa State University Iowa Environmental Mesonet (IEM) website. Iowa State IEM collects environmental data from cooperating members with observing networks. The data are stored and made available on that website. You may toggle the year to see data ranging back to 2004. Data recorded prior to 2004 is not available.