| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 8.7° | — | 42.2mm | 4.8 | 54 |
| February | 9° | — | 51.4mm | 6.7 | 51 |
| March | 11.9° | — | 118.7mm | 9.8 | 54 |
| April | 16.2° | — | 150.3mm | 11.1 | 66 |
| May | 20.2° | — | 144.1mm | 11.3 | 77 |
| June | 22.9° | — | 149.1mm | 12.5 | 75 |
| July | 26.6° | — | 152.7mm | 14.2 | 72 |
| August | 28.1° | — | 138.1mm | 10.6 | 74 |
| September | 25.5° | — | 174.7mm | 11.7 | 77 |
| October | 21.1° | — | 213.7mm | 10.1 | 80 |
| November | 16.4° | — | 84.3mm | 8 | 72 |
| December | 11.2° | — | 63.8mm | 5.9 | 60 |
January in Iwaki averages a daily high of 8.7°C. Expect roughly 4.8 wet days totalling 42.2mm. Demanding conditions — pack for it and plan indoor options.
February in Iwaki averages a daily high of 9°C. Expect roughly 6.7 wet days totalling 51.4mm. Demanding conditions — pack for it and plan indoor options.
March in Iwaki averages a daily high of 11.9°C. Expect roughly 9.8 wet days totalling 118.7mm. Demanding conditions — pack for it and plan indoor options.
April in Iwaki averages a daily high of 16.2°C. Expect roughly 11.1 wet days totalling 150.3mm. Generally workable, with some weather to plan around.
May in Iwaki averages a daily high of 20.2°C. Expect roughly 11.3 wet days totalling 144.1mm. Comfortable conditions for being outdoors all day.
June in Iwaki averages a daily high of 22.9°C. Expect roughly 12.5 wet days totalling 149.1mm. Comfortable conditions for being outdoors all day.
July in Iwaki averages a daily high of 26.6°C. Expect roughly 14.2 wet days totalling 152.7mm. Generally workable, with some weather to plan around.
August in Iwaki averages a daily high of 28.1°C. Expect roughly 10.6 wet days totalling 138.1mm. Generally workable, with some weather to plan around.
September in Iwaki averages a daily high of 25.5°C. Expect roughly 11.7 wet days totalling 174.7mm. Comfortable conditions for being outdoors all day.
October in Iwaki averages a daily high of 21.1°C. Expect roughly 10.1 wet days totalling 213.7mm. Comfortable conditions for being outdoors all day.
November in Iwaki averages a daily high of 16.4°C. Expect roughly 8 wet days totalling 84.3mm. Generally workable, with some weather to plan around.
December in Iwaki averages a daily high of 11.2°C. Expect roughly 5.9 wet days totalling 63.8mm. 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. Iwaki peaks at 80.
Based on 30 years of records, May–November scores highest for comfort in Iwaki, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 28.1°C.
October is the wettest, averaging 213.7mm of rain across roughly 10.1 wet days.
January is the coolest month, with average daily highs around 8.7°C.