Noun
weather deck (plural weather decks)
(nautical) A ship's deck which has no overhead protection, which is open to the weather; a ship's uppermost deck.
The uppermost continuous deck may be called the "upper deck", "weather deck", "spar deck", " main deck ", or simply "deck". Source: Internet
The top deck in the hull structure was the upper deck (or weather deck ) which was exposed to the elements in the waist. Source: Internet