Air temperature
Temperature & humidity 2-metre temperature two-metre temperature
Air temperature describes how warm or cold the air is at the measuring site. It differs from ground-surface temperature and from a feels-like temperature.
Making measurements comparable
A thermometer in direct sunshine also responds to the heating of its own casing. Weather stations therefore shield the sensor from radiation while allowing air to circulate around it. In Germany, the usual air-temperature measurement is two metres above ground; exact heights can differ slightly between international observing networks.
Why the daily maximum comes after midday
Sunlight heats the ground, which transfers heat to the air. Temperature keeps rising while more energy arrives than is lost. On calm, sunny days, the highest temperature therefore often occurs in the afternoon. Clouds, rain or a different air mass can change this pattern.
Three different temperatures
- Air temperature: the shielded measurement, usually in °C here.
- Surface temperature: for example of asphalt, grass or a roof; it may differ greatly.
- Apparent temperature: a calculated comparison that includes other weather influences.
Why location matters
Paved surfaces store heat, while green areas and moist soil behave differently. A station therefore describes its own setting. A road surface may already be icy with air slightly above freezing if the surface cools more strongly.
Comparing measurements
Measurement height, shielding and location matter when comparing temperatures. An annual mean averages a long series; it is neither a typical afternoon temperature nor a value that occurs everywhere in a city at the same time.