Roads seldom flood for any great distance, as the water runs down to fill the low spots. In dips, the water can be quite deep, so it is a good idea to test the depth with a stick first to make sure that you'll be able to get through. Standing water, even when it is shallow can cause aquaplaning. Water under trees and in other areas of shade will be the last to dry.
The assumption that the good grip of modern tyres means you are always safe on wet roads in a...