How do I determine ‘Dew Point Temperature’?

The dew point temperature, commonly referred to as the ‘Dew Point’, is a measure of the amount of moisture in the air.

Consider the air to be like a big sponge that can soak up moisture.  Also consider that this ‘sponge’ can hold different levels of moisture at different temperatures.  As the air gets warmer it is able to hold more moisture.  Conversely, the air can hold less moisture as it cools.

The dew point is the temperature at which the air, if cooled with its current moisture level, can hold no more moisture.  That is, it is ‘saturated’ (with moisture).

It also follows that cooling the air further will result in some form of precipitation – that is, fog, rain, dew, sleet, hail or snow.

The dew point temperature can be calculated from the air temperature and relative humidity, if known.

Relative Humidity is another means of expressing the amount of moisture in the air.  Please see our separate article on Relative Humidity for more information.

Common uses for Dew Point:

The dew point temperature can be a useful predictive tool in combination with other weather sensors, to predict precipitation and frosts. This has applications across several industries and is particularly useful for agriculture and aviation.

Dew point is also used in spraying applications, where it can be used to determine the likelihood of heavy dew overnight, which can impact upon the spray procedures.  If the dew point temperature is close to the temperature expected overnight, then there is an increased likelihood of dew or fog formation.