Heat stress – are you at risk?

Learn more about heat stress and how to prevent it, check  your current heat stress risks and comment on interesting weather conditions.

What is heat stress?

Heat stress is what happens when your body cannot control its temperature properly and gets too hot. Your body may heat up through exercise or just from direct sunlight. When this happens, your body tries to get rid of heat through the skin by sweating. As sweat evaporates from your skin, it also takes heat away with it, leaving your body nice and cool. 

Keeping your body at a comfortable temperature this way is important, because if your body gets too hot it cannot work properly and can lead to:

  • Heat exhaustion – you get sweaty, tired and nauseous. 
  • Heat stroke – you might get mental confusion, feel faint, or in extreme cases, die.
  • Heat cramps – this is when you get painful cramps or spasms of muscles.
  • Fainting – you might lose consciousness for a little while. 
  • Heat rash – small red itchy bumps might appear on your skin. 

Check your current heat stress risk 

Your body might find it harder to get rid of extra heat the higher the temperature is. You might also find it harder to cool your body down if the air is humid, because it's harder for your sweat to evaporate. Any combination of these two factors can put you at greater risk of getting heat stress, as you can see on this table.

You can use the current weather conditions on temperature and humidity to work out how much risk there is in terms of heat stress.

Heat stress chart

Notice that even at 27-30C, when you might not feel particularly hot, there is a danger of getting heat stress if the humidity is high enough.

Try checking your real time local temperature and humidity to see if you are at risk of getting heat stress right now. 

How can we prevent heat stress?

To keep your body from becoming too warm, you can do the following things:

  • Wear loose-fitting, lightweight clothing. Wear a hat to keep the sun off your head and face. 
  • Drink plenty of fluids. Water and/or sports drinks are recommended. You are at risk of heat stress if you lose 1.5% of your body weight through sweating.
  • Try working during cooler hours of the day.

Comment on interesting weather conditions

Please let us know about any interesting weather you notice. This could be related to heat stress or any other interesting weather you see, maybe on holiday or even on the TV. Tell us where, when and what was interesting about the weather.




Bruce Castle

opalroadshow's picture

temperature 29.7c, humidity 43%, risk of heat stress


Bruce Castle

opalroadshow's picture

 It's very hot and water is advisable

Bruce Castle

opalroadshow's picture

Today's weather was really hot and it made sweat roll off my face! 

Bruce Castle

opalroadshow's picture

It's too hot for me today and I feel claustrophobic because there's no wind.  

risley avenue primary class activity

risleyavenue's picture

I spent my holiday in london, it was hot because it was summer time. I was so hot and i was so stressed. So thats how hot my summer was. It was about 30c.

How about swimming

Johanna_Kaschke's picture

swimmers spend around 2 hours in the water working out, the humidity is very high, how can you check they are sweating, and yes when I swim hard I do get hot despite being in a cold pooling