| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 12.1° | — | 50.9mm | 5.1 | 65 |
| February | 13.4° | — | 111.6mm | 8.1 | 63 |
| March | 16.5° | — | 169.5mm | 10.2 | 68 |
| April | 21° | — | 268.6mm | 10.3 | 79 |
| May | 25° | — | 275.9mm | 10.9 | 78 |
| June | 27.3° | — | 383.9mm | 15.9 | 69 |
| July | 31° | — | 374.4mm | 15.2 | 54 |
| August | 32.3° | — | 274.8mm | 13 | 53 |
| September | 29.7° | — | 349.4mm | 13.8 | 62 |
| October | 25.1° | — | 189.8mm | 9.9 | 80 |
| November | 19.7° | — | 129.8mm | 7.7 | 84 |
| December | 14.6° | — | 66.5mm | 6.2 | 70 |
January in Niihama averages a daily high of 12.1°C. Expect roughly 5.1 wet days totalling 50.9mm. Generally workable, with some weather to plan around.
February in Niihama averages a daily high of 13.4°C. Expect roughly 8.1 wet days totalling 111.6mm. Generally workable, with some weather to plan around.
March in Niihama averages a daily high of 16.5°C. Expect roughly 10.2 wet days totalling 169.5mm. Generally workable, with some weather to plan around.
April in Niihama averages a daily high of 21°C. Expect roughly 10.3 wet days totalling 268.6mm. Comfortable conditions for being outdoors all day.
May in Niihama averages a daily high of 25°C. Expect roughly 10.9 wet days totalling 275.9mm. Comfortable conditions for being outdoors all day.
June in Niihama averages a daily high of 27.3°C. Expect roughly 15.9 wet days totalling 383.9mm. Generally workable, with some weather to plan around.
July in Niihama averages a daily high of 31°C. Expect roughly 15.2 wet days totalling 374.4mm. Demanding conditions — pack for it and plan indoor options.
August in Niihama averages a daily high of 32.3°C. Expect roughly 13 wet days totalling 274.8mm. Demanding conditions — pack for it and plan indoor options.
September in Niihama averages a daily high of 29.7°C. Expect roughly 13.8 wet days totalling 349.4mm. Generally workable, with some weather to plan around.
October in Niihama averages a daily high of 25.1°C. Expect roughly 9.9 wet days totalling 189.8mm. Comfortable conditions for being outdoors all day.
November in Niihama averages a daily high of 19.7°C. Expect roughly 7.7 wet days totalling 129.8mm. Comfortable conditions for being outdoors all day.
December in Niihama averages a daily high of 14.6°C. Expect roughly 6.2 wet days totalling 66.5mm. 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. Niihama peaks at 84.
Based on 30 years of records, April–May scores highest for comfort in Niihama, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 32.3°C.
June is the wettest, averaging 383.9mm of rain across roughly 15.9 wet days.
January is the coolest month, with average daily highs around 12.1°C.