| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 8.3° | — | 91.8mm | 14 | 35 |
| February | 9.7° | — | 65.6mm | 11 | 45 |
| March | 13.3° | — | 99mm | 16 | 49 |
| April | 17.9° | — | 38.9mm | 10 | 73 |
| May | 22.1° | — | 78mm | 7 | 86 |
| June | 25.1° | — | 195.1mm | 14 | 72 |
| July | 29.5° | — | 511.6mm | 22 | 60 |
| August | 30.2° | — | 714.1mm | 22 | 57 |
| September | 26.1° | — | 481.2mm | 14 | 72 |
| October | 21.9° | — | — | — | 94 |
| November | 16.2° | — | — | — | 82 |
| December | 11.4° | — | — | — | 66 |
January in Jeju City averages a daily high of 8.3°C. Expect roughly 14 wet days totalling 91.8mm. Demanding conditions — pack for it and plan indoor options.
February in Jeju City averages a daily high of 9.7°C. Expect roughly 11 wet days totalling 65.6mm. Demanding conditions — pack for it and plan indoor options.
March in Jeju City averages a daily high of 13.3°C. Expect roughly 16 wet days totalling 99mm. Demanding conditions — pack for it and plan indoor options.
April in Jeju City averages a daily high of 17.9°C. Expect roughly 10 wet days totalling 38.9mm. Generally workable, with some weather to plan around.
May in Jeju City averages a daily high of 22.1°C. Expect roughly 7 wet days totalling 78mm. Comfortable conditions for being outdoors all day.
June in Jeju City averages a daily high of 25.1°C. Expect roughly 14 wet days totalling 195.1mm. Generally workable, with some weather to plan around.
July in Jeju City averages a daily high of 29.5°C. Expect roughly 22 wet days totalling 511.6mm. Generally workable, with some weather to plan around.
August in Jeju City averages a daily high of 30.2°C. Expect roughly 22 wet days totalling 714.1mm. Generally workable, with some weather to plan around.
September in Jeju City averages a daily high of 26.1°C. Expect roughly 14 wet days totalling 481.2mm. Generally workable, with some weather to plan around.
October in Jeju City averages a daily high of 21.9°C. Comfortable conditions for being outdoors all day.
November in Jeju City averages a daily high of 16.2°C. Comfortable conditions for being outdoors all day.
December in Jeju City averages a daily high of 11.4°C. Generally workable, with some weather to plan around.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Jeju City peaks at 94.
Based on 30 years of records, May scores highest for comfort in Jeju City, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 30.2°C.
August is the wettest, averaging 714.1mm of rain across roughly 22 wet days.
January is the coolest month, with average daily highs around 8.3°C.