An Etymological Dictionary of Astronomy and Astrophysics

The state of the → atmosphere, mainly with regard to its effects of temperature, cloudiness, rainfall, wind, etc. upon life and human activities. As distinguished from → climate, weather consists of the short-term variations in the atmosphere.

Etymology (EN): M.E., from O.E. weder; cf. M.Du., Du. weder, O.H.G. wetar, Ger. Wetter “storm, wind, weather.”

Etymology (PE): Havâb, short for havâ “weather; air” (see below) + âb→ water, from âb o havâ “weather; climate.”
Havâ, from Ar., probably itself a loanword from Mid.Pers. vây “weather, air,” Av. vayah-, vaya- “weather,” from va- “to blow;” cf. Skt. va-, Gk. aemi- “to blow;” Av. vâta- “wind,” Skt. vata-,
L. ventus, Mod. Pers. bâd “wind.” PIE *we- “to blow;” havâb contraction of havâ + âb “→ water,” from âb o havâ “weather,” literally “water and air.”