Flooding is directly related to precipitation, but finding floods by looking strictly at precipitation data is almost impossible. Average annual precipitation reveals general flooding trends.

For example, flooding has historically been more common during years of higher precipitation. However, the graph of wettest years does not at all match the graph of greatest floods. This is because the precipitation that causes floods is often concentrated into a few weeks or months. Historically, when average precipitation is higher for several years running, it is more likely to flood during that wet period. Such was the case when the years 2007 through 2011 were all wetter than average, resulting in frequent summer floods and serious spring floods in 2009, 2010 and 2011.

The present concern about spring flooding is certainly a result of the wet weather last spring and fall and the heavy snow already this winter, but it is largely the weather of the coming couple of months which will determine the extent of flooding this spring.