Extreme heat is reshaping sports and sport governance faster than many events are ready for. In this article, experts Ollie Jay, Lachlan McIver, Alejandro Saez Reale and Marc Gordon set out what’s at stake, what the science says, and how we can combine knowledge and coordination mechanisms from pitch-side protocols to crucial heat-health action plans – connecting heat science to the people making decisions on worker safety, audience protection, to every single sport.
As the 2026 World Cup kicks off across the Canada, Mexico and the United States, researchers estimate that one in four matches, including the final, might be played out in conditions experts consider hazardous to health. The story of extreme heat hitting hard on both on players, officials and spectators has been covered widely on all major news outlets – but the World Cup is certainly not the first event in which extreme heat has entered the playing field as an opponent.
“Extreme heat has been reshaping sport for years,” says Professor Ollie Jay, Director of the Heat and Health Research Centre at the University of Sydney and Global Heat Health Information Network (GHHIN) expert. “Heat caused Australian Open tennis players to collapse back in 2014 and again in 2018; at the Tokyo olympics, equestrian competitions had to be moved to cooler evening hours because of heat; and football tournaments have been forced to introduce special hydration breaks. What we’re likely to see at this World Cup has been building for a long time, and extreme heat is affecting not only football but all sports.”
Together, Professor Jay and Tennis Australia’s medical team developed the Australian Open Heat Stress Scale, a five-level system that replaced, starting in 2019, the tournament’s previous single-station temperature threshold with real-time measurements of temperature, radiant heat, humidity and wind speed taken courtside across the entire precinct.
“We rebuilt the system from the ground up, integrating real-time measurements of air temperature, radiant heat, humidity and wind speed from five locations, then running that through a player-specific physiological algorithm to produce a five-level heat stress scale with clear, actionable decisions at each level”, explains Jay. “The science existed. What was missing was the commitment to apply it properly.”
Athletes, spectators and workers at risk
However, it’s not only elite athletes who are at risk. Stadiums may employ security guards standing outside for hours without sufficient shade; community races can have volunteer marshals who aren’t covered by the event’s insurance policies; and construction workers may work through scorching heat, finishing a new arena during the hottest months of the year. Spectators may spend hours queuing into the stadiums – or be exposed to heat watching outdoor screenings in poorly shaded environments.
According to the World Meteorological Organization, global average temperatures are likely to continue at or near record levels in the next five years, giving rise to an increased frequency, duration and severity of heat extremes, not to mention the combination of heat and humidity. Sports governing bodies are likely to be forced to ask hard questions about scheduling, infrastructure and accountability.
“Cooling breaks, local heat stress monitoring and revised evidence-based heat protocols are all much needed steps in the right direction. While some global guidance on heat in sport exists, it is still highly fragmented, unevenly enforced, and sport-specific on a global scale. Future solutions should draw on the latest science of “how hot is too hot?” for different sports and different participants. The direction of travel is away from single fixed temperature cut-offs and toward tailored environmental thresholds for action, set against the physiological strain a given sport actually produces”, says Jay.
According to Jay, in practice that means anchoring decisions on how fast core temperature is likely to rise, with fluid losses and other factors compounding that strain, rather than on air temperature alone – or on other thermal indices that combine temperature, humidity, solar radiation, and wind speed to estimate how hard it is for your body to cool itself.
Some sports are already adopting this approach. Cricket Australia uses a Heat Stress Risk Index with separate calculators for adult and adolescent players, and the National Rugby League has introduced extended half-time breaks informed by its own sport-specific heat stress tool. Both adapt the response to the conditions and to who is on the field.
VAR for extreme heat in sports
“Heat illness can escalate quickly from fatigue and cramps to life-threatening heat stroke,” says Dr Lachlan McIver, Health Advisor at the WHO-WMO Climate and Health Joint Office. “What worries us is that exertional heat illness is often underreported in sport: symptoms can mimic other conditions, and without proper surveillance, we are almost certainly missing the true burden. In addition to public health advice and heat-health action plans, collaborating with the World Health Organization and partners, we’d need a VAR for extreme heat in sports!”
The Video Assistant Referee football, known as VAR, is there to catch what the naked eye misses. This so the referee can make the right decision at the right moment of the game, in a way supporting the very foundations and structure of the game. Formally introduced into football’s Laws of the Game in 2018, VAR became a gamechanger. Although not perfect, it helped define protocols, clear thresholds for interventions, and referee accuracy rose close to 99%, according to FIFA and IFAB reports.
“You could say that VAR improved not only accuracy but helped strengthen the governance of the game itself. When it comes to extreme heat, the knowledge and tools to manage extreme heat already exist,” says Alejandro Saez Reale, who coordinates the Global Heat Health Information Network hosted by the WHO-WMO Climate and Health Joint Office. “Just as wheels and suitcases existed separately for centuries but only a few decades ago someone thought of combining them into a single product, what we need now is to combine knowledge and coordination mechanisms, connecting heat science to the people making decisions on worker safety, audience protection, for every single sport.”
Teamwork for solutions
The United Nations Office for Disaster Risk Reduction (UNDRR), working hand-in-glove with GHHIN and WMO, as well as national and international experts, developed the Extreme Heat Risk Governance Framework and Toolkit, which was launched at the UN Climate Change Conference (COP30) in 2025. Designed to help governments coordinate preventative, management and response measures across sectors and geographies, it was developed with more than 130 experts and institutions.
The Framework gives governments, businesses, investors, urban planners and public health authorities a shared, adaptable structure and approach that can shape societies’ approach to decision-making, investment and heat action: one that sport’s governing bodies can draw on directly to move beyond ad hoc cooling breaks toward more coordinated, systemic, and evidence-based heat policies.
“Called for by countries, the Extreme Heat Risk Governance Framework presents a vital opportunity to tackle this threat to functioning societies”, says Marc Gordon, UNDRR’s Global Lead for Extreme Heat Risk Reduction. “Governments, cities, investors and businesses now have the possibility to take integrated and proactive action to limit the increase of extreme heat, as well as manage and adapt to its impacts. Extreme heat does not respect the boundaries between countries, nor sport, health, labour, energy, transportation and urban planning, and neither should the response. We cannot air-condition our way out of this.”