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What's the real difference between 天気 and 天候? In at least one of my dictionaries, 天候 just redirects to 天気.
I've always thought (read: "felt") that 天候 is the general "concept" of weather, or even climate
秋の天候 - "the [type of] weather in the fall"; 北海道の天候 - "the climate of Hokkaido"
whereas 天気 seems to be the actual tangible weather.
明日の天気は雨です - "Tomorrow (the actual weather) will be rain"; 天気予報 - "weather (not climate) forecast"
EDIT: After looking a bit more through the different definitions, it seems that 気候 is more closely related to "climate" than 天候.