Cold temperatures. London winters can bring about frigid temperatures, which can cause pipes to freeze and later rupture. Burst pipes are a common cause of flooding. Flooding. London may be on the perimeter of southwestern Ontario’s snow belt, but it still gets hit with heavy snowfall. The ensuing spring thaw has the potential to trigger flooding as well. The city is also no stranger to powerful thunderstorms. These are sometimes accompanied by downpours, which in turn can cause flooding. Earthquakes. Powerful, destructive earthquakes are rare in southwestern Ontario, but London does indeed experience seismic activity. However, any activity often scores low on the Richter scale.