Locating an Outdoor Thermometer and Hygrometer
Even though most basic models of home weather stations are capable of measuring temperature and humidity, getting accurate readings about these conditions is not always easy. Your thermometer and hygrometer must be sited correctly in order to limit the effects of certain factors, like solar radiation, on the data.
In weather stations, thermometers and hygrometers are usually integrated into one temperature humidity sensor. This type of sensor should never be placed in an area where the sun’s rays strike it directly, unless it has a solar radiation shield or ventilated housing to protect it. More often than not, however, it is best to just place it in a shaded area that is sheltered from rainfall. Siting the sensor at the edge of the area beneath the eaves of your house is a good idea.
The standard height above ground for a thermometer hygrometer is 1.5 meters. They need to be sited in an area that is open and level, ideally above trimmed grass which would allow for ventilation. Unless the area you live in is almost entirely composed of rocky terrain, natural groundcover, or dirt, do not put the sensor in areas with these kinds of terrain. Nor on a steep slope because of the effect gravity has on water and air flow.
There a couple of other guidelines that you should keep in mind when locating an area to place your temperature humidity sensor. Though this is not always possible, avoid local heating and cooling sources as well as nearby obstructions by a length of four times the height of the obstruction or more. Also avoid areas where precipitation collects or pools. And lastly, DO NOT site your sensor under a tree or any kind of plant.