Weather data from Mumbles, Swansea.


Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is colder or hotter.

Todays temperatures

Outdoor temperature from midnight.

Indoor/outdoor temperature comparison 

Temperature, Relative Humidity and Heat Index.

Relative Humidity (RH) is the most common measure of humidity. It measures how close the air is to being saturated – that is how much water vapour there is in the air compared to how much there could be at that temperature. Warmer air can hold more water vapour because there is more energy available. If the RH of the air is 100% then it is fully saturated.

During a period of high temperatures, air with very high RH is very uncomfortable as the saturated air affects our body’s cooling mechanism. The air cannot easily contain anymore water as a vapour and so cannot effectively evaporate the sweat from our skin.

In low temperatures, air with very high RH can make us feel cooler. This is because there is more water vapour close to our skin and since water is a much better conductor than dry air, the cold temperature of the air is conducted to our skin, making us feel cooler.