Onitsha Monthly Rainfall & Precipitation
This page shows both the average monthly rainfall and the number of rainy days in Onitsha, Nigeria. The figures are based on a 30-year period (1990–2020) to provide a reliable average. Let's explore the details to provide you with a complete overview.
Onitsha experiences significant rainfall throughout the year, averaging 1463 mm (58 in) of precipitation annually. However, this abundant rainfall is not evenly distributed, with a distinct dry and rainy season during certain months. You can clearly see this in our monthly precipitation graphs below.
Monthly Precipitation Levels
The average number of days each month with precipitation (> 0.2 mm (0.01 in))
The seasons in Onitsha, bring significant changes in precipitation. The wettest month, September, receives heavy rainfall, with an average of 227 mm (8.9 in) of precipitation. This rainfall is distributed across 19 rainy days.
In contrast, the driest month, December, experiences much less rainfall, totaling 9.9 mm (0.4 in) over a single rainy day. These distinct seasonal differences provide diverse experiences throughout the year.September, the wettest month, has a maximum daytime temperature of 31°C (88°F). During the driest month December you can expect a temperature of 35°C (95°F). For more detailed insights into the city's temperatures, visit our Onitsha Temperature page.
Explore Onitsha's Historical Precipitation: 1987-2026
Browse day-by-day precipitation records for Onitsha spanning 40 years. Select any month and year to see actual rainfall and snowfall recorded on each day.
Annual Rainfall in Nigeria: City Comparison
The map below shows the annual precipitation across Nigeria. You can also select the different months in case you are interested in a specific month.
heavy rainfall
high
moderate
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Onitsha vs World: Rainfall Compared
Onitsha's average annual precipitation is 1463 mm (58 in). Let's compare this to some popular worldwide tourist destinations:
The city of Rome, Italy, has an average annual precipitation of 832 mm (33 in), spread fairly evenly throughout the year.
Beijing, China, receives 560 mm (22 in) of annual precipitation, concentrated in the summer months.
In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.
Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm (66 in) of annual rainfall, with the heaviest precipitation occurring during September and October.
Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.
Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.
Precipitation has a very strong role in determining the local climate and ecosystem:
- Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
- Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.
- Mawsynram in India is noted as being the wettest place on earth, with over 11 meters (36 feet) of rain falling every year.
- In contrast, Antofagasta in Chile is among the driest places on the planet, getting less than 0.1mm (0.004 inches) per year, with some years recording virtually no rainfall.
- Nearly 1,650 thunderstorm cells are estimated over the planet at any given time.
For more detailed information about Onitsha's weather, including sunshine hours, humidity levels, and temperature data, visit our Onitsha Climate page.
