Bo climate — normals and trends
Bo (Sierra Leone) has a tropical monsoon climate (Am) under the Köppen-Geiger classification. Its mean annual temperature is 25.5 °C and it receives 2,518 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 March (27.5 °C on average) and the coldest is August (23.8 °C). Rainfall peaks in August.
Bo averages 0 frost days, 198 hot days (≥ 30 °C) and 245 rainy days per year.
Bo has warmed by +1.5 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The hottest day of the period reached 40.6 °C (on 21 February 2016) and the coldest 14.9 °C (on 9 January 1957).
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
BoSouthern Province
- coords
- 7.96°, -11.74°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
25.5°C
Average daily high
30.5°C
Average daily low
22.4°C
Annual rainfall
2,518mm
Sunshine / day
8.7h
Mean relative humidity
85%
Average peak wind
9.5km/h
Seasonal range
3.7°C
Frost days (< 0 °C)
0 d/yr
Hot days (≥ 30 °C)
198 d/yr
Rainy days (≥ 1 mm)
245 d/yr
Annual snowfall
0.0 cm
Average feels-like high
35.6 °C
Average feels-like low
26.7 °C
Average peak gust
24.6 km/h
Tropical nights (≥ 20 °C)
358 d/yr
Solar radiation
16.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.5 °C
since 1940
+0.2 °C per decade · r² = 0.72 · 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
40.6 °C
21 February 2016
Coldest day
14.9 °C
9 January 1957
Wettest day
289 mm
2 September 1952
Windiest day
20.5 km/h
27 August 2017
Strongest gust
54.4 km/h
12 July 1953
Hottest feels-like
47.3 °C
27 April 2024
Coldest feels-like
13.2 °C
6 January 1989
Sunniest day
12.0 h
5 June 2022
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 | 36.7 °C | +3.8 °C | 8 mm | -13 mm |
| Feb | 38.1 °C | +3.9 °C | 6 mm | -20 mm |
| Mar | 37.5 °C | +3.5 °C | 32 mm | -29 mm |
| Apr | 35.0 °C | +2.7 °C | 93 mm | -44 mm |
| May | 31.9 °C | +1.3 °C | 198 mm | -61 mm |
| Jun | 30.4 °C | +1.1 °C | 183 mm | -136 mm |
| Jul | 27.9 °C | +0.1 °C | 450 mm | +58 mm |
| Aug | 27.4 °C | +0.1 °C | 600 mm | +151 mm |
| Sep | 28.1 °C | 0.0 °C | 794 mm | +356 mm |
| Oct | 29.8 °C | +0.8 °C | 273 mm | +1 mm |
| Nov | 30.1 °C | +0.5 °C | 118 mm | +5 mm |
| Dec | 30.6 °C | -0.1 °C | 51 mm | +18 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 Bo?
Bo has a tropical monsoon climate (Köppen Am). Over 1940-2025, the average annual temperature is 25.5 °C and it receives 2,518 mm of precipitation per year.
What is the hottest day ever recorded in Bo?
The hottest day measured in Bo between 1940 and 2025 was 21 February 2016, reaching 40.6 °C.
What is the coldest day in Bo?
The coldest day measured in Bo between 1940 and 2025 was 9 January 1957, at 14.9 °C.
Does it snow in Bo?
Almost never: Bo sees virtually no snow, with about 0 frost days per year.
Has the climate of Bo warmed?
Yes: Bo warmed by +1.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Bo?
The wettest day measured in Bo between 1940 and 2025 was 2 September 1952, with 289 mm of rain in 24 hours.
What was the windiest day in Bo?
The windiest day measured in Bo between 1940 and 2025 was 27 August 2017, with winds reaching 20.5 km/h.
What is the warmest month in Bo?
The warmest month in Bo is March (27.5 °C on average); the coldest is August (23.8 °C).
How much does it rain in Bo?
Bo receives on average 2,518 mm of precipitation per year, spread over about 245 rainy days.
Is it sunny in Bo?
Bo gets on average 8.7 hours of sunshine per day, roughly 3,175 hours per year over 1940-2025.
Are there tropical nights in Bo?
Yes: Bo has on average 358 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Bo?
In Bo, between 1940 and 2025, the highest apparent temperature reached 47.3 °C on 27 April 2024, and the lowest was 13.2 °C on 6 January 1989.
Compare Bo with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Bo