News

What is a 'heat dome' and why is it super-heating Australia?

Source Weatherzone Wed 28 Jan 2026

The term 'heat dome' has appeared frequently in the media this week with regard to this week's persistent heatwave across a broad area of southeastern Australia. The heatwave is remarkable for both its longevity and extreme temperatures, with numerous records already broken. It’s as though a large part of the country is living under a dome of heat. But what exactly is a heat dome? A heat dome refers to a slow-moving, large high-pressure system in the upper atmosphere which effectively traps and intensifies a hot airmass underneath it. A common analogy used to describe the effects of such a system is that it’s like a lid on a pot which stops heat from escaping. Heat domes suppress the upward movement of air and therefore the formation of rain-bearing clouds. They also prevent other weather systems from intruding and disrupting the persistent heat. Extreme heat continues to circulate over central/eastern Australia, under a persistent upper-level high. The system is expected to break down on the weekend. pic.twitter.com/Rg7q5nsBkv — Andrew Miskelly (@andrewmiskelly) January 27, 2026 Is heat dome an official meteorological term? The term 'heat dome' is one of those weather buzzwords that is becoming more popular. While the BoM does not include it in its official glossary of weather terms, the American Meteorological Society does. So it’s somewhere between "official" weather jargon and a useful (albeit somewhat colloquial) piece of terminology, depending on your location. Why is this week’s heat dome so extreme and persistent? One specific factor at play this week is the influence of ex-Tropical Cyclone Luana, which crossed Western Australia's Kimberley coastline as a category two system on Saturday before becoming a tropical low which is currently still active over WA’s interior. Ex-Tropical Cyclone Luana helped intensify the heatwave by sending upper-level air towards the high pressure system, which then settled towards the surface and increased temperatures further. "What goes up must come down. Air moving upwards in the tropics forming cloud rain and tropical lows or cyclones, then comes down over more southern latitudes," Weatherzone meteorologist Jess Miskelly explains. It should also be noted that the background influence of climate change is an underlying factor in extreme heatwaves in Australia. Australia's mean temperature has increased by around 1.6°C since 1910. Image: Annual mean temperature anomalies in Australia from 1910 to 2025. Source: BoM. What next for the current heatwave? The heatwave will continue to grip a broad area of southeastern Australia between now and Saturday, with temperatures possibly approaching 50°C in parts of four Australian states. After Victoria reached a state record 48.9°C on Tuesday, Wednesday’s highest readings appear likely to occur in western NSW, southwest Queensland and the northwest of SA. On Thursday and Friday, northern and eastern SA look most likely to see the hottest temperatures, with the tiny town of Marree in the state’s North East Pastoral forecast district expected to nudge 50°C on Thursday. It's extremely rare to see 50°C observations at any Australian location – a temperature threshold that has been reliably measured only seven times in Australia, most recently in 2022 at three locations in the Pilbara region of northwest WA. - Weatherzone © Weatherzone 2026