As temperatures hit a high of 46.3C in Sicily, fire crews battled blazes in Greece and the Swiss Alps.
Scientists say climate change is making heatwaves longer, more intense and more frequent.
Across the world, millions of people are being impacted by extreme weather; from soaring temperatures in the US and China, to heavy rainfall in East Asia.
The World Meteorological Organization (WMO) says heatwaves will become more severe in the years ahead, and that extreme weather patterns highlight the need for more climate action.
