Are heat domes becoming more common in North America?

The number of heat domes in North America has increased every year since 1940, a recent climatology study found. The rise in heat domes corresponds with an increase in extreme heat due to human-caused climate change, the study found. A heat dome is a large, warm, high-pressure air mass that traps hot air and suppresses precipitation for several days to over a week. The number of heat domes in northwestern North America is projected to nearly double by 2080 if carbon emissions continue at high levels. A heat dome parked over the Western U.S. in July led to record highs in several states, with temperatures peaking at 115 degrees in Miles City, Montana.