Bolu climate

Name: Bolu
Address: TR

Bolu is warmest in August, with average highs of 26 °C, and coldest in January, when nights average -2.8 °C. May is the wettest month (104 mm) and July the driest (47 mm). Figures are 1991–2020 climate normals.

Across a full year Bolu averages 990 mm of rain, 62 days above 25 °C and 80 days below freezing.

Turkey · population 184,682 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 26 °C
Coldest month January -2.8 °C
Driest month July 47 mm
Wettest month May 104 mm
Least cloud August 39 % cloud
Hottest on record August 36 °C
Coldest on record February -21 °C

What to expectBolu through the year

Bolu has a clear annual cycle: average daily highs run from 4.9 °C in January to 26 °C in August, a swing of 20 °C in mean temperature across the year.

Counted across a normal year, 62 days a year reach 25 °C, 10 of them reach 30 °C, 80 nights drop below freezing. The warmest reading in the 1991–2020 record is 36 °C, in August.

Rain is strongly seasonal. May averages 104 mm against 47 mm in July — 2.2 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	4.9 °C	89 mm	68 %
February	6.2 °C	88 mm	67 %
March	9.9 °C	104 mm	66 %
April	15.2 °C	97 mm	62 %
May	19.7 °C	104 mm	58 %
June	22.8 °C	93 mm	49 %
July	25.5 °C	47 mm	40 %
August	26.4 °C	50 mm	39 %
September	23.1 °C	64 mm	46 %
October	18.3 °C	87 mm	55 %
November	12.3 °C	74 mm	57 %
December	6.7 °C	93 mm	67 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	4.9 °C	-2.8 °C	0.8 °C	15.0 °C	-19.4 °C	0	0	21
February	6.2 °C	-2.6 °C	1.7 °C	21.4 °C	-21.2 °C	0	0	19
March	9.9 °C	0.2 °C	5.0 °C	25.2 °C	-15.2 °C	0	0	14
April	15.2 °C	4.2 °C	9.9 °C	29.2 °C	-11.1 °C	1	0	3
May	19.7 °C	9.0 °C	14.6 °C	31.0 °C	0.4 °C	4	0	0
June	22.8 °C	12.7 °C	18.0 °C	33.2 °C	4.2 °C	8	1	0
July	25.5 °C	14.9 °C	20.4 °C	36.3 °C	8.6 °C	17	3	0
August	26.4 °C	15.6 °C	20.8 °C	36.4 °C	9.1 °C	21	4	0
September	23.1 °C	12.2 °C	17.4 °C	35.6 °C	3.6 °C	10	2	0
October	18.3 °C	8.4 °C	13.0 °C	31.5 °C	-5.6 °C	3	0	0
November	12.3 °C	2.7 °C	7.0 °C	24.9 °C	-15.0 °C	0	0	6
December	6.7 °C	-1.0 °C	2.5 °C	20.3 °C	-18.1 °C	0	0	17

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	89 mm	13	9.6 h/day	68 %	84 %	9.8 km/h
February	88 mm	13	11 h/day	67 %	82 %	10 km/h
March	104 mm	14	12 h/day	66 %	80 %	11 km/h
April	97 mm	14	13 h/day	62 %	78 %	10 km/h
May	104 mm	15	14 h/day	58 %	80 %	9.5 km/h
June	93 mm	13	15 h/day	49 %	80 %	9.8 km/h
July	47 mm	8	15 h/day	40 %	77 %	11 km/h
August	50 mm	8	14 h/day	39 %	75 %	11 km/h
September	64 mm	9	12 h/day	46 %	76 %	9.6 km/h
October	87 mm	11	11 h/day	55 %	79 %	8.8 km/h
November	74 mm	10	9.9 h/day	57 %	80 %	9.2 km/h
December	93 mm	13	9.3 h/day	67 %	84 %	9.6 km/h

How Bolu compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
Bolu	26 °C	-2.8 °C	990 mm	62
Düzce · Turkey	27 °C	-0.6 °C	1,072 mm	83
Adapazarı · Turkey	28 °C	0.01 °C	918 mm	93
Ankara · Turkey	31 °C	-2.7 °C	420 mm	115
Eskişehir · Turkey	29 °C	-3.3 °C	413 mm	97
İzmit · Turkey	28 °C	1.4 °C	919 mm	104
Gölbaşı · Turkey	30 °C	-3.4 °C	431 mm	105

Where Bolu ranks

Ranking	Position	Value
Places with the best weather in Asia in July	15th of 50	86/100
Places with the best weather in Asia in August	45th of 50	85/100
The coolest places in Asia in June	45th of 50	23 °C

Planning a trip? See the best time to visit Bolu.

QuestionsCommon questions about Bolu’s climate

When is the best time to visit Bolu?

That depends on what you want, so the honest answer is a comparison rather than a single month. June, July, August sit closest to 20 °C on average, August is the warmest month and July the driest. The month-by-month table above has the full picture.

How hot does Bolu get?

In August, the warmest month, daily highs average 26 °C. About 10 days a year pass 30 °C. The highest value in the 1991–2020 record is 36 °C.

How cold does it get in winter?

Nights average -2.8 °C in January, the coldest month. A normal year has 80 nights below freezing.

Which month is wettest in Bolu?

May, averaging 104 mm over 15 days with rain. The driest month is July with 47 mm. The year as a whole averages 990 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in Bolu rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Data point: 40.736°, 31.606° (the coordinates the reanalysis values are taken for)
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.