Are bikes more prone to punctures after a spell of rainfall/flooding? We've had an unusually wet winter and flooding has been a problem in my area. Now that the weather has improved and cycling is possible/pleasurable again I'm finding I'm getting many more punctures than I would normally. The kids too, on their bikes. Is this just a run of bad luck or is there a connection with the wet winter? Has the flooding washed more debris onto the road? Perhaps this is a well known problem but I haven't noticed it before.

When the tires are wet the debris sticks to it. A lot gets thrown off as the wheel rotates but any that is sharp and that survives one turn of the wheel gets hammered in when it hits the road. As @mattnz said, the water also lubricates the sharp object as it goes in.

In another answer, I have recommended to brush your tires, but that it not really feasible in the wet because the debris is mostly invisible.