A heat wave is a prolonged period of excessively hot weather, which may be accompanied by excessive humidity. The term is relative to the usual weather in the area, so temperatures that people from a hotter climate find normal can be a heat wave if they are outside the normal pattern for a cooler area. The term is applied both to "ordinary" weather variations and to extraordinary spells of heat which may only occur once a century.

Some regions of the globe are more susceptible to heat waves than others, such Mediterranean-type climates with a summer dry spell which on certain years becomes much hotter than usual.

Severe heat waves can lead to deaths from hyperthermia, especially among elderly people. If accompanied by drought which dries out vegetation, heat waves can lead to wildfires.

To remain safe during heat waves, see Hot Weather Tips

Major Heat Waves

• Indian heat wave
• British Heat Wave of 1976
• Heat Wave of 1980
• Chicago Heat Wave of 1995
• European Heat Wave of 2003

Also See

• Natural disaster
• Global warming
• Weather