January – April: These are great months to visit Colombo and the west coast of Sri Lanka as rainfall is low and temperatures are pleasant, although be warned they do steadily rise in late March and April is often the hottest month of the year in Colombo with highs of up to 35°C.
May-August: May is the start of the rainy season in Colombo and visitors should be prepared to get wet, with an average of 371mm falling throughout the month. Temperatures are high too, making it a tough month to travel in. The heavy rain tends to continue throughout June, but tails off in July, with August often being quite a good time of year to visit Colombo and Sri Lanka as a whole.
September – December: Although unpredictable, often the first half of September sees a window of sunshine and relatively low rainfall, making it a good time to visit Colombo and Sri Lanka’s west coast. But as the month draws to a close, a second rainy spell begins in earnest and October and November are wet months. The rain can continue into December, but usually stops by the middle of the month, making Sri Lanka’s west coast beaches a great place to spend the Christmas and New Year holiday. Temperatures throughout these months remain consistently in the late 20°Cs.