It's too hot for April and temperatures across states are well above normal. But when it gets really concerning is when the temperature crosses what's called the wet-bulb temperature. We saw that 13 people died of heatstroke in Maharashtra, so let's understand what this temperature is that indicates when the heat can be lethal for us. This measure is a combination of temperature and humidity. It essentially tells us at what level our bodies will be unable to cool themselves down by sweating and when they could be prone to heat strokes. The name comes from how it is measured. If you slide a wet cloth over the bulb of a thermometer, the evaporating water from the cloth will cool the thermometer down. So the lowest temperature that a thermometer can be cooled down to after evaporation is called the wet-bulb temperature.