"Under the weather."

[Queen_Bruin]

How did this phrase become “feeling ill”? Sorry if it’s been answered before, but my search-fu is very poor today.

[Exapno_Mapcase]

Not a definitive answer, but a best historical guess from wordorigins.org

Under the Weather

This phrase meaning ill dates to 1827 and, according to the OED2, is an Americanism. The phrase probably derives from the idea that the weather can affect your mood and health.

Isil claims that it is a clipped form of the nautical phrase under the weather bow, a reference to the side of the ship’s bow that is taking the brunt of rough seas, and is a reference to seasickness.

Partridge, refers to a British/Australian nautical use of the phrase to mean drunk. This usage is from the original Americanism. Isil may have confused the two senses.

[Diceman]

I’m feeling “under the weather” right now. Rain often causes me to get a headache, as is the case right now. I think it’s my sinuses.