Software Application Profile: A real-time surveillance system for monitoring heat exposure and its health impacts - presenting the Rio de Janeiro Heat Dashboard
This paper presents the Rio de Janeiro Heat Dashboard, a real-time R/Shiny surveillance system that integrates climatic and health data to monitor heat exposure, classify alert levels, and track health impacts as a core component of Brazil's first municipal heat protocol.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
The sun is a constant companion, but when it burns with unusual intensity, it becomes a silent killer. For decades, scientists and public health officials have known that extreme heat does more than just make people uncomfortable; it strains the human body, leading to heatstroke, heart failure, and death. As the planet warms, these scorching periods are becoming longer and more frequent, turning a seasonal nuisance into a recurring public health crisis. To fight back, cities around the world have begun building early warning systems. These are not just weather reports; they are integrated networks that watch the temperature, predict dangerous spikes, and immediately alert hospitals and city planners so they can act before people get sick. The goal is simple: to see the heat coming and prepare the community to survive it.
In Rio de Janeiro, Brazil, this concept has been turned into a living, breathing digital tool called the Rio Heat Dashboard. Developed by a team of researchers and public health workers, this software application acts as a real-time command center for the city's response to extreme heat. Unlike traditional weather forecasts that might simply say "it will be hot," this system watches the city's temperature and humidity minute by minute, calculates a "heat index" that reflects how the air actually feels to a human body, and then cross-references that data with hospital visits and death records. The result is a platform that tells city leaders not just that the heat is dangerous, but exactly how dangerous it is right now, and how many people are already suffering because of it.
The dashboard was built using a flexible coding framework that allows it to run smoothly on standard computers, making it accessible to the city's health secretariat and emergency operations teams. It pulls data from three different sources: national weather stations, airport weather monitors, and local municipal sensors. Every fifteen minutes, an automated script gathers the latest temperature and humidity readings from these stations and calculates a single, unified picture of the city's heat exposure. To look ahead, the system also downloads global weather forecasts three times a day from six different international weather models, including those from Germany, Europe, the United States, Canada, Japan, and France. By combining these diverse predictions, the system can see up to a week into the future, giving officials a crucial head start on planning.
What makes this tool truly unique is how it connects the weather directly to human health. While most heat warnings stop at the meteorological data, the Rio dashboard includes a module that tracks the immediate impact on the population. It gathers daily data from primary care clinics and emergency rooms, as well as weekly updates on mortality records. When a heat event occurs, the system automatically compares the number of people visiting doctors or dying that day against the average number of visits or deaths for that same day of the week over the past year. This allows the team to see, in near real-time, if a spike in hospital visits is actually caused by the heat. For example, during a severe heat event in January 2025, the dashboard showed that emergency visits jumped by 35.8 percent and deaths from natural causes rose by 16.3 percent, providing concrete evidence of the crisis as it unfolded.
The system operates on a clear set of rules that trigger specific actions. It classifies heat days into levels, ranging from mild to extreme, based on how long the heat stays above certain thresholds and how high the heat index climbs. When the system predicts that the city will reach a critical level, it sends an alert to the meteorologists and health officials. If the prediction holds true and the city actually hits that dangerous threshold, the alert triggers a formal response. This might involve opening cooling centers for the public, suspending outdoor work, or issuing urgent warnings to the population. The dashboard played a pivotal role in January 2025, when it helped the city prepare for and manage its first-ever "Level 4" heat event, a four-day period of extreme danger that required immediate and coordinated action from the mayor's office and health services.
Despite its success, the creators of the dashboard are honest about its limitations. The weather stations are not spread evenly across the city, meaning some densely populated neighborhoods might be hotter than the average reading suggests. The global weather models used for forecasting are also quite large, covering broad areas that might smooth out the specific, intense heat pockets found in a city as complex as Rio. Furthermore, the health calculations are relatively simple, comparing today's numbers to last year's averages without adjusting for other factors like air pollution or flu outbreaks. However, the team is already working to fix these gaps by installing twenty-one new, low-cost sensors across the city to get a finer, more accurate picture of local heat.
The true power of this project lies in its openness. The entire software code is available for anyone to download and study, allowing other cities to adapt the system for their own needs. By sharing the tools and the methods, the researchers in Rio are not just protecting their own city; they are providing a blueprint for how any community can build a bridge between weather data and human health. In a world where extreme heat is becoming a regular threat, the Rio Heat Dashboard offers a clear, practical way to watch the sun, count the cost, and save lives.
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