Introduction 

Every December we are asked the same question: was it a bad year for extreme weather? And each year, the answer becomes more unequivocal: yes. Fossil fuel emissions continue to rise, driving global temperatures upward and fueling increasingly destructive climate extremes across every continent.

Although 2025 was slightly cooler than 2024 globally, it was still far hotter than almost any other year on record (Copernicus 2025) and the impacts of this hotness were unmistakable. This report reviews some of the worst extreme weather events of 2025 the WWA team has studied, documenting the severe consequences of a warming climate and revealing, once again, how unprepared we remain. Across the 22 extreme events we analysed in depth, heatwaves, floods, storms, droughts and wildfires claimed lives, destroyed communities; and wiped out crops. Together, these events paint a stark picture of the escalating risks we face in a warming world. 

At the close of 2025, this report underscores that even in a year that had weak La Nina conditions (NASA, 2025), that lead to lower sea surface temperatures, global temperatures remained very high and significant harm from human-induced climate change is very real. It is not a future threat, but a present day reality. 

Key messages 

• In 2025, extreme weather events continued to occur at concerning levels. Although the natural modes of climate variability, such as El Nino were in a cooler phase, human-driven greenhouse gas emissions meant global temperatures were exceptionally high. These elevated temperatures intensified prolonged heatwaves, worsened drought conditions and fire weather, and increased the extreme rainfall and winds associated with severe storms and floods that resulted in thousands of fatalities and displaced millions of people. The events of 2025 demonstrate the growing risks already present at approximately 1.3°C of anthropogenic warming and reinforce the urgent necessity of accelerating the transition away from fossil fuels.
• Since 2015, when the Paris Agreement was signed, global warming has increased by  0.3°C. This seemingly small rise has already made extreme heat significantly more frequent, adding 11 extra hot days per year on average, and is projected to dramatically escalate with further warming. If policies are fully implemented, the Paris Agreement has helped lower projected warming from 4°C to 2.6°C – a substantial decrease that would nonetheless create a dangerously hot world. Revisiting some of the recent heatwaves studied in previous years such as extreme heat in the Amazon or Burkina Faso and Mali, we found these events to have become almost ten times more likely since 2015, highlighting that every fraction of a degree matters.
• The impacts of 2025’s extreme events are driven by local, context-specific vulnerabilities but in many cases we find the same patterns across the world. Our study in South Sudan highlighted that women are disproportionately affected by extreme heat due to their concentration in informal, heat-exposed work such as agriculture and street vending, along with having limited resources and low literacy rates. Globally women carry an unequal burden, e.g. due to their underrepresentation in leadership and unpaid caring responsibilities often increasing their exposure to dangerously high temperatures and associated long-term health risks. Extreme heat further disrupts education, leading to school closures that reinforce gender inequalities.
• This year highlighted again, in stark terms, how unfairly the consequences of human-induced climate change are distributed, consistently hitting those who are already marginalised within their societies the hardest. But the inequity goes deeper: the scientific evidence base itself is uneven. Many of our studies in 2025 focused on heavy rainfall events in the Global South, and time and again we found that gaps in observational data and the reliance on climate models developed primarily for the Global North prevented us from drawing confident conclusions. This unequal foundation in climate science mirrors the broader injustices of the climate crisis.
• The events of 2025 make it clear that while we urgently need to transition away from fossil fuels, we also must invest in adaptation measures. Many deaths and other impacts could be prevented with timely action. But events like Hurricane Melissa highlight the limits of preparedness and adaptation: when an intense storm strikes small islands such as Jamaica and other Caribbean nations, even relatively high levels of preparedness cannot prevent extreme losses and damage. This underscores that adaptation alone is not enough; rapid emission reductions remain essential to avoid the worst impacts of climate change.