Yes, DRY is a Scrabble word!

Letter values in Scrabble US: D 2, R 1, Y 4.

Is it a valid word?

DRY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

free from liquid or moisture; lacking natural or normal moisture or depleted of water; or no longer wet
humorously sarcastic or mocking
lacking moisture or volatile components
opposed to or prohibiting the production and sale of alcoholic beverages
not producing milk
(of liquor) having a low residual sugar content because of decomposition of sugar during fermentation
without a mucous or watery discharge; a small child with a dry nose"
not shedding tears
lacking interest or stimulation; dull and lifeless
used of solid substances in contrast with liquid ones
unproductive especially of the expected results
having no adornment or coloration
(of food) eaten without a spread or sauce or other garnish
having a large proportion of strong liquor
lacking warmth or emotional involvement
practicing complete abstinence from alcoholic beverages; I happen to be teetotal"

Also: dry out.