[4] A 2022 United Nations report used the term "wildfire" to distinguish "an unusual or extraordinary free-burning vegetation fire which may be started maliciously, accidentally, or through natural means, that negatively influences social, economic, or environmental values".

They cause giant thunderstorms, which often have little rain but with a strong potential for lightning, which can easily create and spread new fires.

[7] A megafire can be caused by various factors, such as high temperatures, drought, human activities, and poor health of forests.

[3] A 2022 United Nations report said that, at the end of the 21st century, the probability of a major wildfire occurring somewhere in the world in any given year—an event "similar to Australia's 2019–2020 Black Summer or the huge Arctic fires in 2020"—will have increased by 31% to 57%.

[13] By early 2019, in the Mediterranean Basin, the countries affected by such fires included Spain, Portugal, Turkey, and Greece.

[11] At the end of 2019, Brazil, Congo, Russia, and the United States had suffered from megafires on a scale described as "unprecedented".