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Military Forts and Voluntary Observers Database

Weather data from 450 US stations operating during the period, 1820-1892 were keyed and more than 350 of these stations were quality controlled under NOAA Climate Data Base Modernization (CDMP) funding. This web site provides information about these 19th Century Forts and Voluntary Observers Database, referred to as FORTS data.

The U.S. Army forts recorded daily weather observations starting in the early 1800s.  In the mid- to late 1800s, volunteer observer networks were managed by the Smithsonian Institution and the U.S. Department of Agriculture.  These station networks eventually evolved into the Weather Bureau's Cooperative Observer Network, which continues to collect data today for the National Weather Service. 

Go to GIS station map
This interactive map of 19th century station locations shows if quality control was completed, and is color-coded by the stations' first year of data. Includes Alaska.

These data provide a link between the more recent instrument records and paleoclimate records such as tree ring reconstructions. The National Archives and Records Administration holds the 1800s records on microfilm.  These records were scanned and indexed, and are available on-line through the National Center for Environmental Information (NCEI) and off-line from the MRCC service office. See the image inventory page for further information.

Thirty-nine distinct data types were identified for digitization, including various observations of temperature, pressure, precipitation, wind, clouds, state of the weather, river gauge height, and surface water temperature.

A series of quality control tests and procedures were applied to much of the digitized data to assure the digitized data accurately represents the observations recorded on the original documents. As funding permits, the quality control continues.

A comprehensive set of metadata was developed to complement the data set. These metadata help document changes in instrumentation and observation practices by identifying changes in the forms used by the observers. The metadata includes detailed information about each station as recorded on the forms, such as station name and location, and barometer correction and other instrument adjustments, when available.

The following is currently available through this web site:

  1. A monthly inventory of all images by month and year available for each station, as available in the NOAA EV2 web archive, showing the extent and completeness of records for each station.
  2. A list of stations selected for keying of the daily weather data shows the current status of the Project, including stations for which keying is complete.
  3. A list of stations indicating the completeness of keying and quality control and whether the data are available.
  4. A compilation of sample standard forms used in the 19th Century allows for searching based on desired weather observation types or period.
  5. Observation histories for selected stations in PDF format. These histories include maps of the observation stations, photos and illustrations, as well as chronology of locations and elevations.
  6. Quality controlled data by station can be obtained in the Forts Data 3200 format with all variables, and also as two *.csv files. One file has daily temperature and precipitation variables only, and the second a chronology of known station identifiers, locations and observers.

Please contact the MRCC Service Office if you have questions or would like to obtain keyed, quality-controlled FORTS data.