Want to know the best way not to die in a flood? Know when they're coming and the seasons in which they're most popular ;). Of course this is much said much easier as I'm writing this from a cozy warm house with the sun shining outside. But knowing when floods occur could provide you with the valuable time you need to get your family and GO!
How Long After It Rains Does It Flood?
You've usually got about six hours after the heavy rain before the ground has become oversaturated to the point of flooding. However, if it starts raining intensely and continues for more than 30 minutes as a constant downpour the time span shortens to half an hour to one hour. But if it's just a light rain, then you've got six hours before you have to worry at all.
Now for the overly scientific answer:
Floods occur when volume of water contained by the shores of water or the banks of a water way exceeds the body's capacity. The water moves above and outward from the typical area it occupies. The major causes of floods are heavy rains, melting snow or a blockage of water flow in a river.
When Is The Flood Season?
In most parts of the US flood season falls between March and June. This is when the right conditions come together often enough to bring heavy rains, and it's usually not one rain that causes a flood, rather it's the constant rain over weeks or months that lead to floods.
There are the freak flash floods that happen every now and then, but the waters recede quickly enough to not cause any real damage like standing water does.