| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -0.1° | — | 42.6mm | 6.7 | 32 |
| February | 0.5° | — | 50.1mm | 7.5 | 30 |
| March | 4.5° | — | 114.2mm | 10.9 | 29 |
| April | 11° | — | 178mm | 12.3 | 47 |
| May | 15.8° | — | 172.5mm | 12.8 | 61 |
| June | 18.7° | — | 253.8mm | 15.6 | 66 |
| July | 22.8° | — | 271.2mm | 18.6 | 70 |
| August | 23.5° | — | 301.5mm | 18.1 | 70 |
| September | 19.3° | — | 354.1mm | 15.4 | 68 |
| October | 13.8° | — | 191.6mm | 12.4 | 55 |
| November | 8.8° | — | 96.7mm | 7.9 | 48 |
| December | 2.6° | — | 62.9mm | 8.1 | 29 |
January in Nikkō averages a daily high of -0.1°C. Expect roughly 6.7 wet days totalling 42.6mm. A hard month to visit for comfort alone.
February in Nikkō averages a daily high of 0.5°C. Expect roughly 7.5 wet days totalling 50.1mm. A hard month to visit for comfort alone.
March in Nikkō averages a daily high of 4.5°C. Expect roughly 10.9 wet days totalling 114.2mm. A hard month to visit for comfort alone.
April in Nikkō averages a daily high of 11°C. Expect roughly 12.3 wet days totalling 178mm. Demanding conditions — pack for it and plan indoor options.
May in Nikkō averages a daily high of 15.8°C. Expect roughly 12.8 wet days totalling 172.5mm. Generally workable, with some weather to plan around.
June in Nikkō averages a daily high of 18.7°C. Expect roughly 15.6 wet days totalling 253.8mm. Generally workable, with some weather to plan around.
July in Nikkō averages a daily high of 22.8°C. Expect roughly 18.6 wet days totalling 271.2mm. Generally workable, with some weather to plan around.
August in Nikkō averages a daily high of 23.5°C. Expect roughly 18.1 wet days totalling 301.5mm. Generally workable, with some weather to plan around.
September in Nikkō averages a daily high of 19.3°C. Expect roughly 15.4 wet days totalling 354.1mm. Generally workable, with some weather to plan around.
October in Nikkō averages a daily high of 13.8°C. Expect roughly 12.4 wet days totalling 191.6mm. Generally workable, with some weather to plan around.
November in Nikkō averages a daily high of 8.8°C. Expect roughly 7.9 wet days totalling 96.7mm. Demanding conditions — pack for it and plan indoor options.
December in Nikkō averages a daily high of 2.6°C. Expect roughly 8.1 wet days totalling 62.9mm. A hard month to visit for comfort alone.
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. Nikkō peaks at 70.
Based on 30 years of records, June–September scores highest for comfort in Nikkō, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 23.5°C.
September is the wettest, averaging 354.1mm of rain across roughly 15.4 wet days.
January is the coolest month, with average daily highs around -0.1°C.