The São Paulo Red Cross works with vulnerable populations, and during winter, one of the biggest challenges is the severe cold. Every year, people living on the streets die from hypothermia, yet cold weather is rarely treated as a humanitarian crisis. The briefing was clear: demonstrate that the cold kills and that the temperature felt on the streets is far more severe than official forecasts suggest. Based on the organization’s experience, it was understood that the highest volume of donations occurs on the coldest nights of the year.

The challenge was to create more nights with that same sense of urgency, even when thermometers weren’t hitting extreme lows. The goal was to drive donations, boost engagement, and shift public perception about the cold, necessitating a change in how weather forecasts are communicated – a simple, accessible, and powerful solution that can save lives.

Weather forecasts show the same temperature for everyone, but they don’t reflect what it feels like for those living on the streets. This led to the creation of Critical Wind Chill: a new unit of measurement designed to reflect the cold from the perspective of people in extreme vulnerability. This new metric takes into account factors like hunger, wet clothing, wind, humidity, and poor sleeping conditions. Backed by its experience on the streets, the São Paulo Red Cross brought these variables together to propose a more honest way of communicating the impact of cold weather.

Critical Wind Chill replaced the traditional forecast across digital and physical media, sparking empathy, mobilization, and donations. This simple yet powerful idea shows that by redefining the cold, lives can be saved.