Under the weather… Where does that expression come from?

Keeping watch onboard sailing ships was a boring and tedious job, but the worst watch station was on the “weather” (windward) side of the bow. The sailor who was assigned to this station was subject to the constant pitching and rolling of the ship. By the end of his watch, he would be soaked from the waves crashing over the bow. A sailor who was assigned to this unpleasant duty was said to be “under the weather.” Sometimes, these men fell ill and died as a result of the assignment, which is why today “under the weather” is used to refer to someone suffering from an illness. A related theory claims that ill sailors were sent below deck (or “under the weather”) if they were feeling sick.

Captain Penny, Sail Nelson