There is no official definition of a heat wave. It is widely recognized though as a sustained period of hot weather.
The problem of course with this type of explanation is defining what is meant by 'sustained' and 'hot'. Hot to someone in London could be described as mild by someone in Nairobi. While sustained could mean 10 days to someone in New York but this would be only a short period of time, in terms of weather, to a person in Mexico City.
There are different definitions of a heat wave around the world and some countries have a varying definition of the concept depending on regional factors. In the USA, a heat wave is usually defined as a period of at least two or more days of excessively hot weather. In the north east, a heat wave is typically defined as three consecutive days where the temperature reaches or exceeds 32 degrees C but this can also depend on humidity levels.
The same does not apply to drier climates within the same country. This definition can be contrasted with the one from Adelaide, Australia, where it is five consecutive days at or above 35 degrees C.
Some organizations have attempted to establish a global definition of the term. The World Meteorological Organization's recommended definition is the most widely known although it has not been adopted around the world. The organization says a heat wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 degrees C.
Heat waves in the USA are considered a lethal weather phenomenon with the average number of fatalities associated with them being around 400.
The problem of course with this type of explanation is defining what is meant by 'sustained' and 'hot'. Hot to someone in London could be described as mild by someone in Nairobi. While sustained could mean 10 days to someone in New York but this would be only a short period of time, in terms of weather, to a person in Mexico City.
There are different definitions of a heat wave around the world and some countries have a varying definition of the concept depending on regional factors. In the USA, a heat wave is usually defined as a period of at least two or more days of excessively hot weather. In the north east, a heat wave is typically defined as three consecutive days where the temperature reaches or exceeds 32 degrees C but this can also depend on humidity levels.
The same does not apply to drier climates within the same country. This definition can be contrasted with the one from Adelaide, Australia, where it is five consecutive days at or above 35 degrees C.
Some organizations have attempted to establish a global definition of the term. The World Meteorological Organization's recommended definition is the most widely known although it has not been adopted around the world. The organization says a heat wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 degrees C.
Heat waves in the USA are considered a lethal weather phenomenon with the average number of fatalities associated with them being around 400.
