Bolu climate
Bolu (Turkey) has a humid subtropical climate (Köppen Cfa). The average temperature over the year is 12 °C54 °F, and about 561 mm22 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Bolu climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 439 | −326 | 033 | 612.4 |
| Feb | 744 | −229 | 236 | 502.0 |
| Mar | 1253 | 133 | 643 | 552.2 |
| Apr | 1763 | 541 | 1152 | 451.8 |
| May | 2272 | 1050 | 1661 | 592.3 |
| Jun | 2679 | 1356 | 2068 | 592.3 |
| Jul | 3086 | 1660 | 2373 | 241.0 |
| Aug | 3187 | 1660 | 2374 | 230.9 |
| Sep | 2679 | 1355 | 1967 | 331.3 |
| Oct | 2067 | 847 | 1457 | 491.9 |
| Nov | 1355 | 337 | 846 | 421.6 |
| Dec | 643 | −130 | 236 | 602.4 |
| Year | 3187 | −326 | 1254 | 56122 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 91% | 80% | 1.7 | 9:33 |
| Feb | 84% | 75% | 2.6 | 10:35 |
| Mar | 75% | 71% | 3.7 | 11:49 |
| Apr | 69% | 65% | 4.9 | 13:15 |
| May | 68% | 60% | 5.9 | 14:26 |
| Jun | 67% | 48% | 6.7 | 15:05 |
| Jul | 61% | 35% | 7.1 | 14:49 |
| Aug | 59% | 33% | 6.4 | 13:47 |
| Sep | 62% | 43% | 4.9 | 12:24 |
| Oct | 70% | 55% | 3.3 | 11:02 |
| Nov | 76% | 60% | 2.3 | 9:51 |
| Dec | 87% | 75% | 1.6 | 9:16 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Bolu is like
The warmest month is August, with an average high of 31 °C87 °F and a low of 16 °C60 °F. The coldest is January, when highs average 4 °C39 °F and lows −3 °C26 °F. Seasons are strongly marked: the warmest month is on average 22.9 °C41.2 °F warmer than the coldest.
Annual precipitation is moderate at about 561 mm22 in. The wettest three-month stretch is December–February, which brings 31% of the annual total. The wettest month is January (61 mm2.4 in), the driest is August (23 mm0.9 in).
Relative humidity ranges from 59% in August to 91% in January. The clearest skies (lowest average cloud amount, 33%) are typical of August. Average wind speed near the ground ranges from 7 km/h (4 mph) in October to 9 km/h (6 mph) in March. Daylight lasts from about 9.3 hours in December to 15.1 hours in June.
Best time to visit Bolu
Based on these averages, the most comfortable months for sightseeing and outdoor activities are May and June and September and October: average highs of 20 °C67 °F to 26 °C79 °F with 33 mm1.3 in to 59 mm2.3 in of precipitation per month.
The most challenging month is January, which is cold, with average highs of 4 °C39 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Bolu
- Winter (December–February) — highs 439 to 7 °C44 °F, lows −326 to −1 °C30 °F, about 57 mm2.3 in of precipitation a month. Pack a warm coat, layers and closed shoes and shoes with good grip, as frost is common.
- Spring (March–May) — highs 1253 to 22 °C72 °F, lows 133 to 10 °C50 °F, about 53 mm2.1 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket and an extra layer for the cooler mornings and evenings.
- Summer (June–August) — highs 2679 to 31 °C87 °F, lows 1356 to 16 °C60 °F, about 36 mm1.4 in of precipitation a month. Pack light summer clothes such as T-shirts, shorts or light dresses and an extra layer for the cooler mornings and evenings.
- Autumn (September–November) — highs 1355 to 26 °C79 °F, lows 337 to 13 °C55 °F, about 41 mm1.6 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
How Bolu compares
Compared with Düzce, about 39 km to the west, Bolu is on average 2.5 °C4.5 °F cooler and receives 26% less precipitation (561 mm22 in vs 753 mm30 in). The difference is largest in January (4.6 °C8.3 °F cooler).
Of the 87 places in Turkey covered by World Climates, Bolu is the 72nd warmest by annual mean temperature and the 47th wettest by annual precipitation. See all of them on the Turkey climate page.
Places in other countries with the most similar temperature and rainfall pattern: Ohrid (North Macedonia, Csa), Niš (Serbia, Cfa) and Cherkessk (Russia, Cfa).
Nearby places
- Düzce 39 km · 15 °C58 °F · 753 mm30 in
- Zonguldak 81 km · 15 °C59 °F · 922 mm36 in
- Karabük 100 km · 15 °C58 °F · 682 mm27 in
- Adapazarı 101 km · 15 °C59 °F · 725 mm29 in
- Ankara 139 km · 12 °C54 °F · 419 mm16 in
- Eskişehir 141 km · 12 °C54 °F · 497 mm20 in
- İzmit 141 km · 15 °C58 °F · 734 mm29 in
- Gölbaşı 147 km · 11 °C52 °F · 432 mm17 in
Frequently asked questions
What is the warmest month in Bolu?
August is the warmest month in Bolu, with an average high of 31 °C (87 °F) and an average low of 16 °C (60 °F).
What is the coldest month in Bolu?
January is the coldest month, with an average high of 4 °C (39 °F) and an average low of -3 °C (26 °F).
When does it rain the most in Bolu?
January is the wettest month with about 61 mm (2.4 in) of precipitation; August is the driest with about 23 mm (0.9 in).
What is the best time to visit Bolu?
Judging by long-term averages, the most comfortable months are May and June and September and October.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 1,277 m, while Bolu lies at about 733 m. Temperatures on this page were therefore adjusted by +3.5 °C6.4 °F using the standard lapse rate of 6.5 °C per 1,000 m.