As summer approaches and the risk of extreme heat increases, it is worth recalling what happened last year. The summer of 2024 placed Belgrade among the cities experiencing record-breaking heat waves, with temperatures soaring above 40°C during several consecutive days, according to the Serbian Meteorological Service. While extreme heat is becoming more frequent across Europe, as the European Environment Agency reports, the consequences for urban economies and infrastructure, particularly the lack of green infrastructure, are often underestimated.
Heat waves are not only a health risk; they also have a direct economic impact. According to the International Labor Organization, heat stress could cause productivity losses equivalent to 80 million full-time jobs globally by 2030. In urban settings, excessive heat increases energy costs, affects employee well-being, and reduces the competitiveness of overheated districts.
Understanding how heat distributes across cities – and what role green infrastructure plays – is becoming a strategic asset for city officials, planners, and developers.
Methodology: using space tech to see the invisible
The analysis focused on identifying the relationship between urban vegetation and surface heat in Belgrade during the extreme heat events of summer 2024. Two major heat waves were selected based on local meteorological records:
- July 13–16, 2024
- August 13–18, 2024
For these periods, the research team obtained Landsat 9 satellite imagery from the USGS Earth Explorer platform. The most suitable cloud-free images corresponded to July 15 and August 15, 2024.
The team calculated the Normalized Difference Vegetation Index (NDVI) for each date using standard remote sensing methods, providing insights into vegetation density and health across the urban area.
The researchers assessed surface temperatures by calculating the Land Surface Temperature (LST) using a customized methodology (full method here).
The resulting images of temperature and vegetation are shown below:
Due to satellite coverage limits, the temperature data did not fully cover some parts of the city. A 30-meter grid was applied to the city, and data on vegetation and temperature were extracted and analyzed for each location. Using Python scripts, the team visualized the data to clearly show how areas with less vegetation experienced significantly higher surface temperatures.
Results & insights: Green infrastructure and the cooling effect of urban vegetation
The scatter plots show the relationship between vegetation (NDVI) and surface temperature (LST) in Belgrade on two hottest days in summer 2024 — July 15 and August 15.
In both cases, the data show a clear negative correlation:
- Areas with more vegetation tend to have lower surface temperatures.
- Extremely high temperatures are mainly found in places with little or no vegetation.
- While lower temperatures can also occur in built-up areas (e.g., shaded or specific urban surfaces), vegetation consistently helps reduce heat at the local level.
These findings highlight the important cooling role of green areas and green infrastructure in the city, especially during extreme heat events. For urban planners and developers, this underlines the value of integrating vegetation into planning, not only for comfort and well-being, but also to mitigate heat-related risks that can impact energy use, productivity, and overall urban resilience. Improving quality of life in cities requires more than solving mobility and transport challenges we discussed earlier (here and here) green infrastructure plays a critical role in shaping healthier, more livable urban environments.
