Several parts combine into one character.

候 is a phonetic-semantic compound: 亻 (person) + 矦 (hóu, originally an archery target / arrow stand — providing the sound). The composite reads as "a person watchful, waiting for a signal" = to scout, observe, await. From this concrete watching-and-waiting image grew an extraordinary range of meanings: scouting → signs / symptoms (what one watches for) → climate (long patterns observed over time) → candidate (one waiting for selection) → inquiry after someone's well-being (asking how they fare).

Korean reading "hu." 氣候 (gihu, climate — used for both weather climate and metaphorical political climate), 徵候 (jinghu, sign / symptom — medical and social), 候補 (hubo, candidate — used in elections), 測候所 (cheukhuso, "observation-waiting station" = weather observation post), 問候 (munhu, "inquiring after well-being" = formal greeting / regards — used in letters: "I always inquire after your well-being").

Mandarin hòu, 4th tone. 候 (hòu), 气候 (qìhòu, climate), 时候 (shíhou, "time-period" = time / moment / when — extremely common: 什么时候 shénme shíhou "when?"), 等候 (děnghòu, to await), 候补 (hòubǔ, candidate / alternate). 时候 (shíhou) is essential everyday vocabulary; almost every Mandarin sentence about time uses 时候.

Japanese on-reading コウ (kō) — 気候 (kikō, climate), 徴候 (chōkō, sign / indication), 測候所 (sokkōjo, weather observation station). And distinctively, the kun-reading そうろう (sōrō) preserves a unique register of Japanese: 候 functioned as the formal copula in Edo-period (江戸時代) writing — the verb meaning "to be / to exist / to be the case" used in samurai correspondence and official documents. The result was an entire prose style called 候文 (sōrōbun, "sōrō-style writing"), which permeated samurai letters, official decrees, and historical novels. Reading classical Japanese requires recognizing 候 as a syntactic marker: 「~に候」 (~ni sōrō, "is in the state of ~"). Modern Japanese has fully replaced sōrō with the polite copula です/ます, but historical-fiction readers and historians still encounter this character constantly.

Memory aid: a person (亻) watching from an arrow stand (矦) — observing, waiting, anticipating signs.