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Monthly averages for Bolu from the Turkish State Meteorological Service, measured over 1929–2025.
The warmest month is August, with an average high of 28 °C. The coldest is January, when the average low is -3.5 °C. January has the most rainy days (15.5 on average), and August the fewest (5.1).
Month by month
| Month | Avg high °C | Avg low °C | Rainy days | Sun (h/day) |
|---|---|---|---|---|
| January | 5.4 | -3.5 | 15.5 | 2 |
| February | 7.2 | -2.5 | 14.4 | 2.9 |
| March | 11.1 | -0.4 | 14.6 | 4 |
| April | 16.7 | 3.6 | 13.3 | 5.3 |
| May | 21.4 | 7.6 | 14 | 6.6 |
| June | 24.7 | 10.5 | 11.7 | 8 |
| July | 27.5 | 12.5 | 6.2 | 8.7 |
| August | 28 | 12.7 | 5.1 | 8.5 |
| September | 24.3 | 9.5 | 7.2 | 6.7 |
| October | 19.3 | 6.2 | 10.7 | 4.7 |
| November | 13.3 | 2.1 | 11.8 | 3.3 |
| December | 7.6 | -1.1 | 14.7 | 2 |
January
In January, Bolu averages a high of 5.4 °C and a low of -3.5 °C, with about 15.5 rainy days.
February
In February, Bolu averages a high of 7.2 °C and a low of -2.5 °C, with about 14.4 rainy days.
March
In March, Bolu averages a high of 11.1 °C and a low of -0.4 °C, with about 14.6 rainy days.
April
In April, Bolu averages a high of 16.7 °C and a low of 3.6 °C, with about 13.3 rainy days.
May
In May, Bolu averages a high of 21.4 °C and a low of 7.6 °C, with about 14 rainy days.
June
In June, Bolu averages a high of 24.7 °C and a low of 10.5 °C, with about 11.7 rainy days.
July
In July, Bolu averages a high of 27.5 °C and a low of 12.5 °C, with about 6.2 rainy days.
August
In August, Bolu averages a high of 28 °C and a low of 12.7 °C, with about 5.1 rainy days.
September
In September, Bolu averages a high of 24.3 °C and a low of 9.5 °C, with about 7.2 rainy days.
October
In October, Bolu averages a high of 19.3 °C and a low of 6.2 °C, with about 10.7 rainy days.
November
In November, Bolu averages a high of 13.3 °C and a low of 2.1 °C, with about 11.8 rainy days.
December
In December, Bolu averages a high of 7.6 °C and a low of -1.1 °C, with about 14.7 rainy days.
Sources
Meteoroloji Genel Müdürlüğü — Bolu (1929–2025) (opens in a new tab)