Heat is rising. Here’s how cities are rising to respond.
“Extreme heat is the new abnormal,” warned UN Secretary-General António Guterres last July, as the world reeled from the hottest days ever recorded. In fact, 2024 broke all previous temperature records. But here’s the alarming part: The real record-breaker is still to come, and it’s likely to hit within the next five years.
This stark warning comes from the latest World Meteorological Organization report, released on 28 May. It forecasts an 80% chance that a new global heat record will be set between now and 2029, and an 86% chance that at least one year will exceed 1.5°C (2.7°F) above preindustrial levels. Human-driven global warming, it warns, is only getting worse.
Guterres paints a bleak reality about heat: “If there is one thing that unites our divided world, it’s that we’re all increasingly feeling the heat.”
In this new and unsettling reality, extreme heat has become the most life-threatening climate-related health risk, disproportionately hitting the most vulnerable the hardest. According to the World Health Organization, extreme heat can lead to a range of health issues, from dehydration, sunburn and contact burns, to heat stroke, lower blood pressure, fainting, and even hyperthermia, ultimately resulting in death.
And nowhere is this truer, or more dangerous, than in our cities.
“Extreme heat is amplified by the urban heat island effect in cities and also cities concentrate vulnerable populations, concentrating risk at the same time,” explains David Jacome-Polit, Head of Resilience Development at ICLEI World Secretariat. He adds, “Extreme heat is also testing critical infrastructure and its capacity to deliver very much needed services.”
Local and regional governments are responding to our new reality through a mix of short- and long-term solutions to keep their communities safer, especially those most at risk.
“However, cities can also offer opportunities, like shaded outdoor areas and safe places for residents to live, travel and recreate. Extreme heat is testing our systems, but it’s also revealing where we can act boldly, collaboratively, and equitably to protect lives and rethink how we build our urban future,” said David Jacome-Polit.
From heat waves to chronic heat: Redefining urban heat response
Phoenix, Arizona, and Miami-Dade County, Florida, are leading a shift in how we understand and respond to heat. In 2024, Phoenix endured 113 consecutive days above 38°C (100°F), contributing to over half of the 608 heat-related deaths in Maricopa County. Miami-Dade experienced similarly prolonged extreme temperatures.
A new study, Where heat does not come in waves: A framework for understanding and managing chronic heat, led by the University of Miami and co-authored by Phoenix and Miami-Dade, makes the case for a major shift in how we understand heat.
Published in May 2025, it argues that framing heat as a chronic crisis allows for more effective, long-term responses to what is becoming a structural threat in many parts of the world. The study distinguishes between acute heat (short, intense spikes) and chronic heat (persistent exposure), showing how current policies often fail to protect people living in constantly hot conditions.
The authors argue that adapting to chronic heat doesn’t require starting from scratch, but rather adjusting existing strategies to reflect the day-to-day realities of those most at risk.
“Cities can adopt layering strategies. On the small scale, creating shade structures at key intersections, greening, pocket parks, can make a difference in felt temperatures. When they can, cities should also be trying to think on a large scale, like green belts and corridors, which can provide cooling over large areas in addition to providing other benefits in terms of wildlife habit and stormwater absorption,” detailed Angelica Greco, Resilience Officer at ICLEI USA, interviewed for America Walks.
Heat leadership for long-term planning
Both Phoenix and Miami-Dade have created dedicated roles and offices focused on heat. Miami-Dade was the first to appoint a Chief Heat Officer in 2021. That same year, Phoenix appointed its own director to run the U.S.’ first publicly funded Office of Heat Response and Mitigation. Both ensure year-round focus on protecting those most at risk -older adults, outdoor workers, people experiencing homelessness, and children.
The City of Phoenix is implementing a range of initiatives. A city ordinance requires landlords to keep rental units below 27.8°C (82°F) with AC systems, and the city’s Cool Callers initiative is a volunteer program that helps prevent heat-related illnesses by making wellness calls to at-risk residents, especially older adults living alone.
Outdoors, the city is building 25 shade structures at key pedestrian intersections and planting over 27,000 trees through the Shade Phoenix Plan. The Cool Pavement Program, in partnership with Arizona State University, has treated over 160 km of streets with reflective coating, reducing surface temperatures by up to 6.7°C (12°F).
Part of these initiatives are included in Phoenix’s Heat Response Plan 2025, which features extended hours at cooling centers from the Heat Relief Network, 24/7 respite shelters, and outreach to vulnerable groups, including a partnership with the Urban Heat Leadership Academy, led by the Nature Conservancy, to support capacity-building among residents.
Miami-Dade County’s Extreme Heat Action Plan outlines 19 actions across three goals: Inform, Prepare, and Protect People; Cool Our Homes and Emergency Facilities; and Cool Our Neighborhoods. Key measures include multilingual awareness campaigns, energy efficiency support for low-income households, and efforts to improve backup cooling systems at critical facilities like evacuation shelters.
The County also leads the Urban Heat Research Group, a collaboration with universities, nonprofits, and local leaders to study and address extreme heat risks. To support local implementation, the County offers a Heat Safety for Workers Toolkit with guides, templates, and training materials to help organizations meet heat safety standards.
How can heat solutions reach the most vulnerable?
Other cities are responding in contextually unique ways. In Rajkot, India, where informal workers and slum dwellers are among the most exposed, the city’s Climate Resilient City Action Plan outlines a wide range of interventions. These include reflective roofs, shaded vending zones, tree planting, and shelters for the urban poor that are designed to mitigate both heat and flooding.
Dedicated efforts are underway to support street vendors—who are especially vulnerable to extreme heat—through a Climate Resilient, Gender-Equitable and Inclusive Street Vending Plan that addresses climate risks, accounts for gender-specific vulnerabilities, and identifies targeted solutions.
In Izmir, Türkiye, the Climate Resilience for Communities Project is working in several neighborhoods to build community-driven heat resilience. From neighborhood-based awareness campaigns to climate preparedness training, the project ensures that no one is left behind in the face of rising temperatures.
In Hobart, Australia, city leaders are focusing on awareness to reach every resident, regardless of income or age. While heatwave frequency may remain stable, longer and more intense hot spells are projected, with growing risks of bushfires.
Mayor Anna Reynolds puts it plainly: “It’s really important that we, as mayors, do what we can to raise awareness in the community about heat and the impact of heat on people’s health. Heat is the silent killer – in Australia, more people die from heat related illnesses and impacts than any other natural disaster. So raising awareness about heat and the impacts of heat stress is a really important part that we can play as community leaders to try and beat the heat.”
Hobart runs public campaigns and works closely with the Tasmanian Bureau of Meteorology to keep residents informed via website, app, and phone alerts.
Using global partnerships to build capacity in cities to combat extreme heat
In 2023, ICLEI and the International Federation of Red Cross and Red Crescent Societies (IFRC), the world’s largest humanitarian network, launched a partnership to empower communities, with a focus on the reduction of climate-induced risks in urban areas, with special attention to vulnerable groups and critical infrastructure.
In 2025, ICLEI joined as a partner to IFRC’s Heat Action Day (HAD). Launched in 2022, Heat Action Day is a global day of awareness and action on extreme heat. The theme of Heat Action Day 2025 is “How to Recognize Heat Exhaustion and Heat Stroke.” The campaign focuses on helping community members to understand the warning signs of heat stroke and how to respond quickly and effectively. Recognizing that cities are on the front lines of this public health emergency, the IFRC has launched the Heatwave Guide for Cities, providing practical tools and real-world examples to help urban areas adapt and respond effectively to extreme heat.
The EU Covenant of Mayors for Climate & Energy has launched a campaign to showcase cities that are prioritizing strategies to address extreme heat. Heat is Europe’s foremost silent climate killer, with heat waves responsible for 95% of climate or weather-related deaths over the past 40 years. In 2023, 48,000 residents died as a result of extreme heat in Europe.
Cities REFRESH is focusing on four main strategies for combating heat: 1) Restoring healthy by creating cooler, safer spaces in cities; 2) rebuilding communities by strengthening social connections and inclusivity; 3) renewing urban design with climate-smart solutions; and 4) reviving local economies. European Covenant signatories can register their heat-related actions with the campaign to be recognized.
Regional cooperation heats up
A new wave of regional collaboration is gaining momentum. ICLEI and the Union of Ibero-American Capital Cities (UCCI) have joined forces to develop the IberAtlas project – Ibero-American Urban Climate Atlas, which maps the urban heat island effect in major Ibero-American cities: Barcelona and Madrid (Spain), Bogotá (Colombia), Buenos Aires (Argentina), Lisbon (Portugal), Montevideo (Uruguay), Quito (Ecuador), and Rio de Janeiro, Belém do Pará, San Salvador, and São Paulo (Brazil). Built on a solid technical-scientific foundation, the project assesses how intensifying heat waves could further strain these urban territories.
The findings informed a joint position paper presented at UNFCCC COP29, calling for more inclusive, science-based urban planning, strengthened local governance, and expanded cooling infrastructure for vulnerable populations.
“Through regional cooperation and technical innovation, we’ve built a powerful tool that maps the heat risks in our cities, helping local governments take strategic, targeted actions. As we face increasingly severe heatwaves, initiatives like this are not just timely; they’re essential to saving lives and building climate-resilient urban futures,” says Stephania Aleixo, Regional Technical Coordinator, ICLEI South America.
As the planet continues to warm, cities are becoming sites of innovation, leadership, and resilience. From emergency response to long-term planning, from local action to global cooperation, cities are not only feeling the heat; they are rising to meet it.
*Featured picture, © City of Phoenix
