Floods can occur at any time. Flood zones are set up via flood plains and are used as guidance on how frequent flooding is likely to occur. A “100-year flood plain,” for example, has a 0.1% chance of flooding in any given year. This classification, however, is based on a statistical basis of thousands of years. This means every thousand years this area will flood 10 times; when such floods will occur, however, is left to chance. You could have three 100-year floods within a five-year period. As our climate changes, historical data isn’t always a reliable predictor of future events.