Background page states: The United States Historical Climatology
Network (USHCN) is a high-quality data set of daily and monthly
records of basic meteorological variables from 1218 observing
stations across the 48 contiguous United States. Daily data
include observations of maximum and minimum temperature,
precipitation amount, snowfall amount, and snow depth; monthly
data consist of monthly-averaged maximum, minimum, and mean
temperature and total monthly precipitation. Most of these
stations are U.S. Cooperative Observing Network stations located
generally in rural locations, while some are National Weather
Service First-Order stations that are often located in more
urbanized environments. The USHCN has been developed over the
years at the National Oceanic and Atmospheric Administration's
(NOAA) National Climatic Data Center (NCDC) to assist in the
detection of regional climate change. Furthermore, it has been
widely used in analyzing U.S. climte. The period of record
varies for each station. USHCN stations