Heat warnings are issued only for categories 3 and 4.

Heat warnings are issued only for categories 3 and 4.

• Effects: Risk of circulatory complaints, physical discomfort
• Behaviour: Protect yourself from exposure to sunlight, avoid physical effort if possible and make sure you drink enough fluid.
• Heat Index HI > 90: min. 3 days. Heatwave with temperatures remaining over the threshold value for three days or more.

• Effects: Increased risk for circulatory complaints, physical discomfort
• Behaviour: Protect yourself from exposure to sunlight, avoid physical effort if possible and make sure you drink enough fluid.
• Heat Index HI > 93: min. 5 days. Extreme heatwave, with temperatures remaining over the threshold value for five days or more.

Heat warnings are issued only for categories 3 and 4, since a heatwave more extreme than this is very unlikely to occur in these latitudes.

Heat warnings are issued only in the summer half year.