Kayakers paddle on the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)

Kayakers paddle on the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)

People cool themselves off along the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)

People cool themselves off along the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)

A kayaker paddles on the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)

People cool themselves off around a cooler along the Vistula River in Warsaw, Poland, July 14, 2024. (Photo by Jaap Arriens/Xinhua)