Dear Tom,
Has this country at any given time experienced complete dry weather from border to border and coast to coast.

Thanks,  Frank C.   Morris

Dear Frank,
It would be almost unimaginable that a precipitation-free period might occur across the 48 contiguous states for even a few hours, let along an entire day. It’s probably never occurred, although records of such events are not kept. While there are times of the year when precipitation is at a minimum, like late September into October when high pressure dominates, there would still be some “orographic-lift” showers caused by air moving up a mountain side. Even in tranquil weather situations, drizzle can occur in foggy areas, and in winter, when large arctic high pressure dominates the nation, lake-effect rain and snow showers will form downwind of bodies of water.