What does heatwave mean?
A heatwave is a prolonged period of unusually hot weather, distinguished from an ordinary hot spell by its intensity, duration, or both. The term is used in everyday conversation and in reports on weather, public health, agriculture, infrastructure, and climate. A heatwave can disrupt daily life by making outdoor conditions dangerous, placing extra strain on hospitals and electricity systems, and damaging crops. It also has broader social significance because prolonged heat is increasingly discussed in relation to climate change, although individual heatwaves cannot automatically be attributed to it. The word is especially memorable because its effects depend not only on how high the daytime temperatures rise but also on how warm the nights remain. Both “heatwave” and “heat wave” are accepted, with the one-word spelling particularly familiar in British usage.
nounA prolonged period of unusually hot weather, often lasting several days or longer and sometimes accompanied by exceptionally high temperatures.
- A sustained period of exceptionally hot weather, usually lasting from several days to several weeks.
"The city issued a public warning as the heatwave continued for a second week."
"Cooling centres opened across the region during the heatwave."
"The heatwave transformed the normally busy park into a place of shaded benches and early-morning exercise."
The regular plural is used when referring to separate heatwave events, as in “the heatwaves of 2020 and 2021.”
"Several severe heatwaves have affected the region in recent years."
The trickiest part of a heatwave may be the night: when the air refuses to cool, the body never gets a clean reset.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Words that share this root
How heatwave is actually used
The word is neutral and common in news, public-health, and environmental contexts. Both “heatwave” and “heat wave” are established spellings; the closed form is common in British English, while the two-word form is also widely used.