pyrocumulonimbus

What does pyrocumulonimbus mean?

Pyrocumulonimbus refers to a thundercloud generated by intense heat, such as that produced by a volcanic eruption and especially by a severe wildfire.

Examples of pyrocumulonimbus

In June and July France had two canicules, or spells of extreme heat, with temperatures at 40°C and above; this parched the land and turned pine forests into tinder. At one point intense heat created a weather phenomenon known as pyrocumulonimbus, whereby smoke from the fire generated its own thunderclouds and lightning that struck the ground and set off new fires.
—The Economist, 1 Aug. 2026

A wildfire near Bordeaux burned hot enough to make its own thunderstorm this week, and the lightning it threw started new fires. It was the first pyrocumulonimbus cloud ever recorded in France, but Canada has seen hundreds of them in the last decade.
—Mason Kossak, The National Post (Canada), 31 July 2026

In 2017, fires in British Columbia and Washington state produced five simultaneous pyrocumulonimbi, which eventually joined into one weather system.
—Leyland Cecco, The Guardian (London), 10 May 2023

Where does pyrocumulonimbus come from?

The prefix pyr- or pyro- in this instance means “produced by or as if by the action of heat,” while cumulonimbus refers to a cumulus cloud having a low base and often spread out in the shape of an anvil extending to great heights. The earliest known use of cumulonimbus in print (to this date) occurred in the early 1990s. The related pyrocumulus, referring to a cumulus cloud formed by water vapor mixed with hot, ashy air (as above a fire or volcano eruption), has been in use since the late 1970s.

How is pyrocumulonimbus used?

Its use is increasing, corresponding with the increasing frequency of such storms.