候 shows a person 亻 in attendance — its old duty was watching and waiting: sentries watched the seasons, courtiers awaited the lord. Waiting and time fused into one character.
候 completes 时候 (time — with 时 you learned): 什么时候? is 'when?'. 气候 is climate — the sky's long waiting pattern; 问候 is to send greetings — words that attend on someone. The old world lives inside it: 候鸟 are migratory birds, 'birds that wait for seasons'. Wherever 候 appears, someone or something is attending patiently.
A person 亻 standing watch — WAITING through TIME.
候鸟 'waiting birds' — migratory birds are named for their patience with seasons, not their flight.