Times when the thermometer is over 30°C day after day can be dangerous. If the humidity is also high, the danger increases. High humidity, meaning lots of moisture in the air, can make a 32°C day feel more like it is 36°C or higher. Weather forecasters often give us the "humidex" -the heat we feel as a combined result of the temperature and the humidity, as well as the actual temperature. Scientists predict that climate change will lead to more and longer heat waves. For most of us this will mean more discomfort, but for others, it could be life threatening.