Average 9am and 3pm relative humidity

At a glance

These relative humidity maps show the 9am and 3pm average annual and average monthly relative humidity distribution across Australia.

What do the maps show?

These maps show the average annual and average monthly 9am and 3pm relative humidity (RH) over the period 1976 to 2005. Average annual RH is calculated by adding 9am or 3pm RH values over a specified period (1976 - 2005) and dividing by the number of years in that period (30 years in this case). Similarly, average monthly 9am and 3pm RH is calculated by adding daily 9am or 3pm values for a selected month and dividing by the number of years in the specified period.

Relative humidity (RH) is an indicator of the moisture content of the air. It is the amount of moisture in the air as a percentage of the amount of moisture the air can actually contain. Warmer air can contain more moisture than cooler air, which means that for a given amount of atmospheric moisture, RH will be lower if the air is warm and higher if the air is cool. This can be seen by comparing the daily 9am maps (higher RH values) with the daily 3pm maps (lower RH values) for any month of the year.

The annual 9am and 3pm RH maps show that RH increases in coastal regions, similar in nature to the distribution of rainfall in the annual rainfall maps. RH tends to be higher in northern Australia due to the wet climate experienced in this region.

How are the values calculated?

RH can be measured in a number of ways using different instruments. Humidity sensors are used in unmanned weather stations to measure RH. In manned stations, wet bulb and dry bulb temperatures are collected and used in the calculation of RH values. RH is also an important factor relating to thermal comfort, and is used in the calculation of thermal stress indices.

Further information

• About the maps - metadata and related information.
• Learn about how humidity is measured and calculated.
• Find out how climate statistics are calculated.
• Information about the range of gridded climate data we can provide.
• Information about additional climate products and other data available from the Bureau of Meteorology.
• Learn about the influences on the Australian climate.
• Explore other topics relating to climate education.
• View recent weather observations.