Environment
A persistent “heat dome” over the central United States this summer could have spillover effects in the Prairies and northwestern Ontario, worsening the outlook for areas already affected by fire and near-drought conditions
Hetxw’ms Gyetxw (Brett Huson) is worried.
From his home in Winnipeg, Huson, a research associate with the Prairie Climate Centre, has watched central and western Canada’s wildfire season roar to an early and extreme start. Nearly 200,000 hectares have burned so far this year in Manitoba alone — seven times the province’s 25-year average. And more than 20,000 people have been evacuated from communities in Alberta, Saskatchewan and Manitoba, including the entire city of Flin Flon, while provincewide states of emergency are in effect in Manitoba and Saskatchewan. With long-term weather models signalling a hot, dry summer across much of the region, this could be just the beginning.
“That’s a very scary thought, to know that we’re in states of emergency right now and it potentially will get worse,” Huson says.
The latest 90-day outlook from the North American Oceanic and Atmospheric Administration (NOAA) shows a high probability for above-normal temperatures and below-normal precipitation for a broad swath of the United States from the Pacific Northwest to Texas. As summer advances, a heat dome is expected to persist over the central United States. That heat dome might occasionally extend across the border, says Rachel Modestino, a meteorologist with Canada’s Weather Network, which issued its own summer outlook last week highlighting the potential for an exceptionally hot and dry summer for parts of central and western Canada.
“There may be times that the heat dome does inch closer into the southern prairies, into northwestern Ontario, bringing those conditions that are not ideal for fire weather: well above normal temperatures, lack of precipitation,” says Modestino. The areas that are currently fire-afflicted are already experiencing abnormally dry and in some cases near-drought conditions, according to the Canadian Drought Monitor, increasing the likelihood that new human- or lightning-caused fires will quickly grow out of control.
Much of Canada experienced what could be described as a more “normal” winter this year, especially compared to the El Niño-fueled warmth and dryness of the winter of 2023-24. Temperatures in the boreal forest, where most of the current fires are burning, were above normal, but precipitation was near or in some cases above normal. That snow pack helps to keep the ground saturated into the spring.
“Winter as a whole set us up pretty well,” Modestino says, “But come the spring, we saw a series of 30-degree days [in the areas experiencing intense fire activity right now] and a lot drier of a pattern, and that set the stage for the high fire danger we’ve been seeing for the past several weeks.”
There was a stretch in mid-May where Winnipeg came close to breaking its all-time May high temperature record, she adds.
Canadians were introduced to the term “heat dome” in summer 2021 when a strong and long-lasting area of high pressure developed over western North America, bringing days of scorching heat to southern B.C. that killed more than 500 people, shattered records and quickly ushered in the conditions for a devastating wildfire that destroyed the village of Lytton in the interior.
Heat domes form when an area of high pressure becomes trapped by a jet stream. Jet streams are narrow, fast moving currents of air in the atmosphere that move weather systems; Canada’s weather is largely influenced by the polar jet that flows west to east around the middle to northern latitudes of the northern hemisphere. The stream is usually fairly straight, but can occasionally become wavy, cutting off weather systems from the normal flow of the wind.
Under the trapped high pressure area, air gets pushed toward the ground, preventing the formation of condensation clouds and rain. The cloudless skies allow more of the sun’s radiation to reach the ground, heating it further and contributing to rapid drying.
“You’re inching closer to drought conditions the longer that high pressure is in place,” says Modestino.
At the fringes of a dome, the temperature contrast can fuel powerful storms. “We call them ‘ring of fire’ thunderstorms because they kind of ride the edge around the heat dome,” says Modestino. If the summer forecast plays out as expected, storms could bring much-needed rainfall to drought- and fire-afflicted areas of the Prairies, but there’s a catch: they can also produce other severe impacts, such as damaging winds (the derecho that swept across southern Ontario and Quebec in May 2022 formed along the edge of a heat dome).
Huson says there’s no doubt that the current emergent fire situation in central and western Canada, and the worrisome temperature and precipitation outlook for summer, are driven by climate warming.
“It’s not just a backdrop, it’s an accelerant,” he says. “Over the past decade we’ve seen the behaviour of fires and weather trends align with the scientific predictions that researchers have been making.”
The Climate Atlas of Canada, a project by the Prairie Climate Centre that combines science, mapping and storytelling into an interactive tool to help Canadians understand future climate scenarios, shows that if the current pace of greenhouse gas emissions continues unchecked, heat waves will become more frequent and more intense by the middle of this century. Historically, heatwaves in Winnipeg have lasted three to four days; by 2051-2080, they could persist for longer than seven days, according to a report by the Prairie Climate Centre. Average daytime and nighttime temperatures will rise almost everywhere across Canada. It’s a recipe for disaster for areas already prone to drought and cyclical fires.
“The data is clear: Canada is warming at more than twice the global average,” says Huson. “We’re going to have warmer temperatures, we’re going to have longer drought periods, and the shifting precipitation patterns are creating ideal conditions for these large-scale wildfires to happen.”
Huson is concerned about the impact of a hot, dry summer on an emergency response apparatus that is already stretched thin.
“We’re not just seeing more fires, we’re seeing the fires behaving in ways that challenge our response systems,” he says. “We’re going to see impacts on infrastructure, agriculture; we’re probably going to see a lot of community health impacts, especially in rural and Indigenous communities. Everyone’s going to need to start to keep things like this in mind if we’re going to make it through.”
Huson’s work at the Prairie Climate Centre has focused on gathering Indigenous knowledges, not only about the scale and pace of ecosystem change, but also how to think and act collectively to bring our systems back into alignment with nature. Huson, who is Gitxsan from the northwest interior of B.C., says allowing First Nations to lead on their own land, acting on knowledge handed down over generations — for example, by using controlled burning to remove excess fuel from the forest and grasslands ahead of the warmest and driest months — can provide a template for a holistic response to climate change.
“The wildfires that we’re seeing, they’re not just an environmental crisis,” says Huson. “We’re dealing with deeper systemic issues in how we relate to the land, how we relate to knowledge and responsibility, so the Indigenous knowledges that come from the land offer us the tools and the framework to rebuild our future.”
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