| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 5.9° | -2.7° | 61.3mm | 15.3 | 18 |
| February | 8.4° | -1.9° | 53.1mm | 13.2 | 31 |
| March | 11.3° | -0.4° | 59.6mm | 15.2 | 39 |
| April | 17.1° | 4.1° | 50.8mm | 12.4 | 66 |
| May | 22° | 8.1° | 67.5mm | 13.8 | 72 |
| June | 25.6° | 11.9° | 77.1mm | 11.4 | 77 |
| July | 28.4° | 13.9° | 29.7mm | 5.3 | 84 |
| August | 28.8° | 14.3° | 18.9mm | 4.2 | 84 |
| September | 25.2° | 11° | 28.9mm | 7.6 | 85 |
| October | 19.5° | 6.8° | 46.9mm | 10.1 | 78 |
| November | 14.1° | 1.9° | 40.1mm | 9.5 | 62 |
| December | 8.2° | -0.5° | 51.4mm | 13.6 | 31 |
January in Bolu averages a daily high of 5.9°C with nights around -2.7°C. Expect roughly 15.3 wet days totalling 61.3mm. A hard month to visit for comfort alone.
February in Bolu averages a daily high of 8.4°C with nights around -1.9°C. Expect roughly 13.2 wet days totalling 53.1mm. A hard month to visit for comfort alone.
March in Bolu averages a daily high of 11.3°C with nights around -0.4°C. Expect roughly 15.2 wet days totalling 59.6mm. Demanding conditions — pack for it and plan indoor options.
April in Bolu averages a daily high of 17.1°C with nights around 4.1°C. Expect roughly 12.4 wet days totalling 50.8mm. Generally workable, with some weather to plan around.
May in Bolu averages a daily high of 22°C with nights around 8.1°C. Expect roughly 13.8 wet days totalling 67.5mm. Generally workable, with some weather to plan around.
June in Bolu averages a daily high of 25.6°C with nights around 11.9°C. Expect roughly 11.4 wet days totalling 77.1mm. Comfortable conditions for being outdoors all day.
July in Bolu averages a daily high of 28.4°C with nights around 13.9°C. Expect roughly 5.3 wet days totalling 29.7mm. Comfortable conditions for being outdoors all day.
August in Bolu averages a daily high of 28.8°C with nights around 14.3°C. Expect roughly 4.2 wet days totalling 18.9mm. Comfortable conditions for being outdoors all day.
September in Bolu averages a daily high of 25.2°C with nights around 11°C. Expect roughly 7.6 wet days totalling 28.9mm. Comfortable conditions for being outdoors all day.
October in Bolu averages a daily high of 19.5°C with nights around 6.8°C. Expect roughly 10.1 wet days totalling 46.9mm. Comfortable conditions for being outdoors all day.
November in Bolu averages a daily high of 14.1°C with nights around 1.9°C. Expect roughly 9.5 wet days totalling 40.1mm. Generally workable, with some weather to plan around.
December in Bolu averages a daily high of 8.2°C with nights around -0.5°C. Expect roughly 13.6 wet days totalling 51.4mm. 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. Bolu peaks at 85.
Based on 30 years of records, June–October scores highest for comfort in Bolu, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 28.8°C.
June is the wettest, averaging 77.1mm of rain across roughly 11.4 wet days.
January is the coolest month, with average daily highs around 5.9°C.