Surface Weather Observations Monthly

Surface Weather Observation 1001 Forms is a set of historical manuscript records for the period 1893-1948. The collection includes two very similar form types: Form 1001, in use by the US Weather Bureau, and Form 1, in use by the US Army and Navy. NCDC Climate Data Modernization Program (CDMP) scanned the vast majority of these forms in order to fill in the observation gap prior to the time when commercial aviation began in the U.S. Many forms contiaining observations taken on foreign soil have not yet been scanned. Observations were recorded two to four times daily beginning as early as 1893 at city Weather Bureau Offices. During the 1930s many of these city stations gradually moved to airport locations.

Through 1936 observations were taken twice daily; then in 1937 the general practice was to record four observations per day. The data elements are as follows: station pressure, sea level pressure, dry and wet bulb temperature, dew point, maximum and minimum temperature, wind direction and speed, precipitation, cloud amount and type, ceiling, state of weather and visibility. It should be noted that not all elements are present for all stations in this dataset, and that ceiling and visibility observations did not begin at the city offices until the 1930's. Official surface weather observation standards can be found in the Circular N manuals. The vast majority of records are available online, but some records are still only available in the physical format only.