Meteorological instruments (or weather instruments), which include meteorological sensors (weather sensors), are used to determine the state of the atmosphere at a given time.
Rain gauges are useful for measuring precipitation.
Thermometers are used to measure the temperature outside.
An anemometer is a device used to measure wind speed.
A hygrometer, a meteorological instrument used to measure the humidity or the amount of water vapor in the air. Humidity is measured using a variety of hygrometers.