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Heat Index

As wind can make it effectively colder, the humidity also affects how hot it feels and how effectively your body can keep itself at a normal temperature. Sometimes the humidity can make it feel colder, but on warmer days, higher humidity increases the heat index to dangerously high levels. Also, strong winds, particularly with very hot, dry air, can be extremely hazardous as the wind adds heat to the body.
Your body produces a lot of heat that we normally radiate off, and we use sweat to cool our bodies down faster when we are producing lots of heat such as when we are walking.
On hot days and when exercise we can run the serious risk of overheating that can cause serious injury and death.

The following tables show index values and the effect they can have on people. These values are for shady locations only. Exposure to full sunshine can increase heat index values by up to 10°C.