The COOP network has provided climate and weather data for over 100 years. Consistency of the
measurements is an attribute of the network, and it has been maintained by rare and/or gradual
change, and established standards for exposure, of instruments over the life of the network. In
order to preserve the integrity of the network, NWS has established standards for
equipment, siting, and exposure.
Temperature sensor siting: The sensor should be mounted 5 feet +/- 1 foot above
the ground. The ground over which the shelter [radiation] is located should be
typical of the surrounding area. A level, open clearing is desirable so the thermometers are freely
ventilated by air flow. Do not install the sensor on a steep slope or in a sheltered hollow unless
it is typical of the area or unless data from that type of site are desired. When possible, the
shelter should be no closer than four times the height of any obstruction (tree, fence, building,
etc.). The sensor should be at least 100 feet from any paved or concrete surface.
Precipitation gauge siting: The exposure of a rain gauge is very important for
obtaining accurate measurements. Gauges should not be located close to isolated obstructions such as
trees and buildings, which may deflect precipitation due to erratic turbulence. To avoid
wind and resulting turbulence problems, do not locate gauges in wide-open spaces or on elevated
sites, such as the tops of buildings. The best site for a gauge is one in which it is
protected in all directions, such as in an opening in a grove of trees. The height of the protection
should not exceed twice its distance from the gauge. As a general rule, the windier the gauge
location is, the greater the precipitation error will be.
Rooftop Temperature Bias