Hunting the heat: four innovative ways to map urban heat
Extreme heat is a pressing urban hazard, magnified by climate change and meteorological events such as heat domes.
Phenomena like the urban heat island effect can push city temperatures far above those of surrounding areas, disproportionately endangering vulnerable communities.
Temperatures in highly paved areas can be up to 12°C higher than in places with urban tree canopies, showing how unevenly heat is distributed across neighbourhoods. Mapping and tracking this heat stress - street by street - is essential to inform early warning systems, urban planning, and public health interventions.
From citizen science to wearable technologies, here are some promising methods being used to monitor and manage urban heat:
1. Smartwatches monitoring heat stress in India
Residents in Ahmedabad, India, have been given smartwatches embedded with heat-tracking features as part of a global study focusing on vulnerable communities.
This global research project has distributed devices in Africa's Burkina Faso, the Pacific island of Niue near New Zealand and in the Sonoran desert region in Mexico.
These wearables record physiological responses to extreme heat, helping researchers understand the efficacy of adaptation measures such as cool roofs.
Participants have reported improved sleep after roofs were treated - demonstrating how personal data can inform broader resilience strategies.
2. Garbage trucks double as rolling heat sensors in the USA
In South Bend, Indiana, researchers at the University of Notre Dame have outfitted municipal garbage trucks with temperature and humidity sensors along their usual routes.
These mobile stations allow for consistent, granular data collection across cities - especially useful for revealing heat stress patterns in under-resourced areas.
The information aids city planners in targeting interventions like tree planting to areas most in need.
3. Citizen science in South African cities
In Johannesburg and Ekurhuleni, volunteers equipped with heat-stress monitors took readings across diverse neighbourhoods to map how heat exposure varies with urban form and history.
Results showed temperature differences of up to 6°c between densely built, underserved townships and greener, affluent suburbs.
The findings underscore how citizen-led data collection can highlight both environmental inequities and heat mitigation opportunities (e.g. shaded green spaces, reflective surfaces).
4. Mapping thermal discomfort through body-felt temperatures in Swiss cities
A recent innovation by Swiss researchers showcased at the 2025 Global Platform on Disaster Risk Reduction focuses not just on ambient temperature but on what the body actually feels.
This method shifts the measurement from instrumental readings to human-centric thermal mapping - using portable sensors on walks through the city- capturing actual heat stress experiences across urban areas.
This approach promises richer, more actionable insights into heat risk.
Turning data into action
Together, these innovations show how cities can move from simply collecting heat data to creating detailed maps of exposure and, ultimately, driving targeted solutions.
Whatever the method, the goal is the same: to pinpoint where heat risk is most severe and act quickly to reduce it.
By turning information into action, urban leaders can design smarter cooling strategies, protect vulnerable populations, and strengthen resilience against the rising threat of extreme heat.
From gathering data to putting solutions in place, mapping where cities are hottest is key to beating the heat.
- WMO Member:
- South Africa