It's about ten years old in popular usage and not really describing anything new https://www.nytimes.com/2011/07/23/us/23dome.html

Eli Jacks, a meteorologist with the National Weather Service in Silver Spring, Md., said that he had no idea where the term “heat dome” originated, and that while he prefers the term “heat wave,” the dome metaphor was “an apt way to describe this huge bubble of hot air.”