Bolu climate — normals and trends
Bolu (Republic of Türkiye) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.0 °C and it receives 1,026 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is August (18.5 °C on average) and the coldest is January (-0.9 °C). Rainfall peaks in May.
Bolu averages 98 frost days, 2 hot days (≥ 30 °C) and 152 rainy days per year.
Bolu has warmed by +2.7 °C between 1940 and 2025, or +0.32 °C per decade. This trend is statistically significant.
The number of frost days there went from about 118 to 78 per year over the period.
The hottest day of the period reached 35.3 °C (on 13 July 2000) and the coldest -24.4 °C (on 2 February 2012).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
BoluBolu
- coords
- 40.74°, 31.61°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.0°C
Average daily high
13.9°C
Average daily low
4.6°C
Annual rainfall
1,026mm
Sunshine / day
9.9h
Mean relative humidity
80%
Average peak wind
9.9km/h
Seasonal range
19.4°C
Frost days (< 0 °C)
98 d/yr
Hot days (≥ 30 °C)
2 d/yr
Rainy days (≥ 1 mm)
152 d/yr
Annual snowfall
175.6 cm
Average feels-like high
12.9 °C
Average feels-like low
2.6 °C
Average peak gust
30.6 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
15.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.7 °C
since 1940
+0.3 °C per decade · r² = 0.59 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
35.3 °C
13 July 2000
Coldest day
-24.4 °C
2 February 2012
Wettest day
57 mm
2 November 1940
Windiest day
33.2 km/h
1 February 2015
Strongest gust
103.3 km/h
26 February 1973
Hottest feels-like
37.9 °C
29 July 2000
Coldest feels-like
-29.9 °C
2 February 2012
Snowiest day
30.3 cm
19 February 1999
Sunniest day
14.0 h
28 June 2025
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 8.4 °C | +5.4 °C | 68 mm | -27 mm |
| Feb | 3.0 °C | -1.3 °C | 71 mm | -19 mm |
| Mar | 14.4 °C | +6.8 °C | 53 mm | -50 mm |
| Apr | 12.5 °C | -0.5 °C | 123 mm | +18 mm |
| May | 18.6 °C | +1.2 °C | 92 mm | -19 mm |
| Jun | 23.2 °C | +2.3 °C | 16 mm | -76 mm |
| Jul | 28.3 °C | +5.0 °C | 8 mm | -47 mm |
| Aug | 27.2 °C | +3.2 °C | 33 mm | -18 mm |
| Sep | 22.4 °C | +1.5 °C | 56 mm | -4 mm |
| Oct | 16.4 °C | +0.2 °C | 147 mm | +66 mm |
| Nov | 15.4 °C | +4.5 °C | 41 mm | -41 mm |
| Dec | 6.8 °C | +1.4 °C | 133 mm | +32 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Bolu?
Bolu has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 9.0 °C and it receives 1,026 mm of precipitation per year.
What is the hottest day ever recorded in Bolu?
The hottest day measured in Bolu between 1940 and 2025 was 13 July 2000, reaching 35.3 °C.
What is the coldest day in Bolu?
The coldest day measured in Bolu between 1940 and 2025 was 2 February 2012, at -24.4 °C.
Does it snow in Bolu?
Yes. Bolu gets on average 175.6 cm of snow per year and has around 98 frost days.
Has the climate of Bolu warmed?
Yes: Bolu warmed by +2.7 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Bolu?
The wettest day measured in Bolu between 1940 and 2025 was 2 November 1940, with 57 mm of rain in 24 hours.
What was the windiest day in Bolu?
The windiest day measured in Bolu between 1940 and 2025 was 1 February 2015, with winds reaching 33.2 km/h.
What is the warmest month in Bolu?
The warmest month in Bolu is August (18.5 °C on average); the coldest is January (-0.9 °C).
How much does it rain in Bolu?
Bolu receives on average 1,026 mm of precipitation per year, spread over about 152 rainy days.
Is it sunny in Bolu?
Bolu gets on average 9.9 hours of sunshine per day, roughly 3,614 hours per year over 1940-2025.
What is the biggest single-day snowfall in Bolu?
The heaviest 24-hour snowfall measured in Bolu between 1940 and 2025 was 19 February 1999, with 30.3 cm.
Are there tropical nights in Bolu?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Bolu.
What was the most extreme apparent temperature in Bolu?
In Bolu, between 1940 and 2025, the highest apparent temperature reached 37.9 °C on 29 July 2000, and the lowest was -29.9 °C on 2 February 2012.
Compare Bolu with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Bolu