This article was updated on 17 March 2022
Have you ever stepped out of the house in the morning and thought, ‘I knew it would be cold, but perhaps not this cold!’
The temperatures that you normally see on our website represent the temperature of the air, but this takes no account of how we actually experience the temperature. It is our ‘feels like’ temperature that gives you a better idea about how the weather will actually feel when you step outdoors, where wind and humidity can make a big difference.
For example, in winter a strong wind can make you feel much colder than the measured temperature would indicate. Conversely on a humid day in summer it can feel uncomfortably hotter than the air temperatures would suggest on their own. The ‘feels like’ temperature takes these factors into account and should allow users to make a better assessment of conditions outdoors.
But how do you actually calculate the ‘feels like’ temperature?
We calculate a ‘feels like’ temperature by taking into account the expected air temperature, relative humidity and the strength of the wind at around 5 feet off the ground (the typical height of a human face!), combined with our understanding of how heat is lost from the human body during cold and windy days.
On windy days the speed of moisture evaporation from your skin increases and serves to move heat away from your body, making it feel colder than it actually is. The exception to this rule, however, is when temperatures climb higher. On warm days, wind chill becomes less significant. Instead, humidity plays a greater role.
When a human perspires, the water in their sweat evaporates. This results in the cooling of the body as heat is carried away from it. When humidity is high, the rate of evaporation and cooling is reduced, resulting in it feeling hotter than it actually is.
Using these facts we use a formula to adjust the air temperature based on our understanding of wind chill at lower temperatures, heat index at higher temperatures and a combination of the two in between.