Colombo Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Colombo. The numbers are calculated over a 30-year period to provide a reliable average. Let’s explore the details in depth to provide you with a complete overview.

Colombo has a relatively rainy climate with high precipitation levels, averaging 2608 mm of rainfall annually.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm)

Colombo can be quite wet during October, receiving approximately 355 mm of precipitation over 16 rainy days.

In contrast January, experiences much drier conditions, with 71 mm of rainfall, spread across 5 rainy days.

October, the wettest month, has a maximum daytime temperature of 30°C. The city receives 202 hours of sunshine in this period. During the driest month January you can expect a temperature of 32°C. For more detailed insights into the city’s temperatures, visit our Colombo Temperature page.

Annual Precipitation in Sri Lanka

The map below shows the annual precipitation across Sri Lanka. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Colombo’s average annual precipitation is 2608 mm. Let’s compare this to some popular worldwide tourist destinations:

In Lisbon, Portugal, the average annual precipitation is 774 mm, characterized by wet winters and dry summers typical of the Mediterranean climate.

Osaka, Japan, experiences 1507 mm of rainfall annually, spread across the year with wetter summers.

In Brisbane, Australia, the annual precipitation is 979 mm, making it wetter than Sydney.

Kuala Lumpur, Malaysia, receives 2529 mm of annual rainfall, characteristic of its equatorial tropical rainforest climate, with consistent rainfall throughout the year and peak months during March and November.

How is Precipitation Measured?

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.

How Does Precipitation Affect Local Climate?

Precipitation has a very strong role in determining the local climate and ecosystem:

• Rainy Seasons: Many parts of the world have well-defined wet seasons where precipitation is distinctly higher. These are normally accompanied by lush vegetation and temperature patterns.
• Dry Seasons: In areas where the climate is either desert or Mediterranean, the amount of precipitation is drastically reduced, leading to a shortage of water and arid conditions.

For more detailed information about Colombo’s weather, including sunshine hours, humidity levels, and temperature data, visit our Colombo Climate page.