What is a Heat Dome?

The popularity of the term “heat dome” as a reference to impactful heat waves has grown substantially in recent years, especially outside of the meteorological community. However, there lacks a clear meteorologically sound and operational definition of what a heat dome is. The term, which is not new, has referred to a hot, persistent area of upper-level high pressure, often associated with a heat wave. A survey of literature and media reports indicates that the term broke into the public dialog during the June 2021 Pacific Northwest heat wave. This event has colloquially become known in many venues, including in several peer reviewed articles, simply as “The Heat Dome”. With justified growing concern over and public attention on the increasing severity of heat waves due to anthropogenic global warming, continued use of the term heat dome has led to a range of interpretations, most commonly in reference to the actual magnitude of the heat. While meteorologists likely have a range of opinions about the rapid adoption, popularity, and use of the term, it appears to be here to stay, and we argue that the meteorology community should work towards developing and clearly communicating a more rigorous definition. Towards this goal, we introduce a working definition, developed using western North America as a case study. Clear communication to the public of the risks posed by heat waves is more important than ever, making deliberate and consistent use of descriptive, meteorologically sound terms critical.