| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 2.2° | -5.7° | 1.6mm | 2 | 29 |
| February | 4.5° | -4.4° | 1.6mm | 2 | 37 |
| March | 10° | 0.8° | 43.1mm | 9 | 48 |
| April | 16.8° | 6.5° | 88.9mm | 8 | 74 |
| May | 21.9° | 11.9° | — | — | 94 |
| June | 24.4° | 16.5° | 42mm | 12 | 76 |
| July | 26.9° | 20.1° | 170.5mm | 20 | 70 |
| August | 27.7° | 21.7° | 475.4mm | 15 | 67 |
| September | 23.4° | 15.7° | — | — | 94 |
| October | 19° | 9.3° | — | — | 91 |
| November | 11.4° | 3° | — | — | 66 |
| December | 4.7° | -4° | — | — | 36 |
January in Wŏnsan averages a daily high of 2.2°C with nights around -5.7°C. Rain is rare — about 2 wet days and 1.6mm across the month. A hard month to visit for comfort alone.
February in Wŏnsan averages a daily high of 4.5°C with nights around -4.4°C. Rain is rare — about 2 wet days and 1.6mm across the month. Demanding conditions — pack for it and plan indoor options.
March in Wŏnsan averages a daily high of 10°C with nights around 0.8°C. Expect roughly 9 wet days totalling 43.1mm. Demanding conditions — pack for it and plan indoor options.
April in Wŏnsan averages a daily high of 16.8°C with nights around 6.5°C. Expect roughly 8 wet days totalling 88.9mm. Generally workable, with some weather to plan around.
May in Wŏnsan averages a daily high of 21.9°C with nights around 11.9°C. Comfortable conditions for being outdoors all day.
June in Wŏnsan averages a daily high of 24.4°C with nights around 16.5°C. Expect roughly 12 wet days totalling 42mm. Comfortable conditions for being outdoors all day.
July in Wŏnsan averages a daily high of 26.9°C with nights around 20.1°C. Expect roughly 20 wet days totalling 170.5mm. Generally workable, with some weather to plan around.
August in Wŏnsan averages a daily high of 27.7°C with nights around 21.7°C. Expect roughly 15 wet days totalling 475.4mm. Generally workable, with some weather to plan around.
September in Wŏnsan averages a daily high of 23.4°C with nights around 15.7°C. Comfortable conditions for being outdoors all day.
October in Wŏnsan averages a daily high of 19°C with nights around 9.3°C. Comfortable conditions for being outdoors all day.
November in Wŏnsan averages a daily high of 11.4°C with nights around 3°C. Generally workable, with some weather to plan around.
December in Wŏnsan averages a daily high of 4.7°C with nights around -4°C. Demanding conditions — pack for it and plan indoor options.
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. Wŏnsan peaks at 94.
Based on 30 years of records, September–October scores highest for comfort in Wŏnsan, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 27.7°C.
August is the wettest, averaging 475.4mm of rain across roughly 15 wet days.
January is the coolest month, with average daily highs around 2.2°C.