A Stevenson's screen is used to shield instruments from precipitation and direct heat radiation from outside sources. The screen allows air to circulate freely and provides a uniform environment in relation to the air outside the screen. These screens are used as part of a standard weather recording station. By exposing thermometers in as near standard conditions as is practical, comparative data can be obtained from different sites if required.
The medium-size screen holds a maximum and minimum thermometers and a pair of thermometers, one wet bulb and one dry bulb, to create a hygrometer. The large screen is designed to hold two recording instruments, thermograph and hair hygrometer and sheathed-pattern thermometers.
A purpose-made metal stand is available to hold the screen at the Met Office recommended height of 1.25m above the ground. The stands can be set into the ground for security.