London sits in the Great Lakes basin in Ontario, where a humid continental climate brings precipitation fairly evenly through the year, with the biggest flood risks coming from spring snowmelt and intense summer thunderstorms.
On the Thames River in southwestern Ontario, the city has a well-documented history of flooding, prompting significant flood-control investment over the decades. Lake-effect weather patterns and the basin’s many rivers mean local flooding can develop quickly during a strong spring melt or a slow-moving summer storm, and Environment Canada’s radar network is a key tool for tracking both. Learn more: Flash Flood Warning Signs on Radar · Open the full Rain Map