The last wide-spread 100-year flood event in Hamilton occurred in 1958.  The Waikato River was last at a 100-year flood level in 1998. Waikato River flooding is affected by rainfall upstream of Hamilton. Flooding in Hamilton, other than in the Waikato River Corridor, is affected by rainfall directly on the city. A 100-year flood event has a 1 % probability of occurring any year.