Millions across eastern US will be under ‘major’ or ‘extreme’ heat risks as a sprawling heat dome bears down on the country just as it prepares to celebrate its 250th Independence Day and hosts the Fifa World Cup.
The heatwave, according to the US National Weather Service, is set to peak through the Fourth of July holiday weekend, one of the busiest outdoor travel and celebration periods on the American calendar — and collide with a run of outdoor FIFA World Cup fixtures in Miami and Kansas City.
How bad, and where
Sweltering conditions have already settled over the US Midwest and South, with forecasters expecting the system to push into the Mid-Atlantic and Northeast before parking over the eastern seaboard.
Temperatures across large swathes of the country are forecast to reach between 35°C and 40.6°C (95°F-105°F). When combined with high humidity levels, the heat index — what the temperature actually feels like to the body — could climb to a range of 38°C and 46°C (100°F-115°F), BBC reported.
More than 150 daily record highs are expected to be tied or broken between Tuesday and Saturday, CNN said, citing the National Weather Service. New York could see back-to-back days above 37.8°C (100°F) on Thursday and Friday, and the heat wave could hit Washington, Charlotte, Cleveland, and Pittsburgh too.
It is not only the daytime highs driving concerns. Meteorologists have warned that night-time temperatures won’t bring much relief, especially in urban areas that could struggle to cool below 26.7°C (80°F). This matters because the body needs to recover after a punishing day.
“Our bodies can’t regulate when the air is so saturated, with how muggy it is,” AccuWeather senior meteorologist Tyler Roys told Bloomberg, adding that the risk of heat-related illnesses will rise across the population, and not just among the elderly.
High humidity keeps the air heavy with moisture, which slows evaporative cooling — the process by which sweat draws heat away from the skin as it evaporates. When humidity is high, sweat evaporates more slowly, so the body’s natural cooling mechanism becomes far less effective even as it works harder.
What’s causing this?
Two separate heat domes are currently forming — one over the south-western US and another over the subtropical Atlantic — and are expected to merge into a single, larger system parked over the centre of the US, Jeff Berardelli, chief meteorologist at Nexstar’s WFLA in Tampa Bay, said.
Nexstar meteorologist Blake Matthews said of the mechanism, “A strong, upper-level high-pressure cell acts like a lid on the atmosphere, compressing and heating the air while also suppressing cloud development and rainfall.”
Berardelli separately linked the pattern to a developing “super El Niño”, which – he said – is injecting additional heat into the atmosphere and altering the jet stream in ways that are amplifying heat domes globally.
In a post on X, he noted that the US heatwave is expected to be followed by another prolonged, record-breaking heat dome over Europe, arriving back-to-back with the continent’s already brutal heat season.
Over the past, temperatures across European countries inched closer or exceeded 40°C. This heat wave, also blamed on a “heat dome” has been linked to at least 1,300 deaths, with the count expected to be far higher. Scientists have said the growing frequency and intensity of heatwaves could not have happened without human-caused global warming and climate crisis.
World Cup matches on way
The heat wave, which will also affect Canada, is arriving in the middle of the World Cup’s Round of 32.
Portugal and Croatia are scheduled to meet in Toronto on Thursday, with conditions expected to feel like the low 30°s Celsius (upper 80°s F) and scattered thunderstorms possible, CNN reported. Toronto is forecast to reach around 35°C (95°F) that day, according to Canada’s orange warning for heat.
In Miami on Friday, Argentina face Cape Verde, with kick-off temperatures expected near 32.2°C (90F) and a heat index in the high 30s to low 40s. A Colombia-Ghana fixture in Kansas City on Friday evening is scheduled to avoid the hottest part of the day but is still expected to face a heat index in the mid-30s.
