Posted on 16/03/2021
1. First Inter-Monsoon Season (March - April)
During this season the typical weather conditions are: thunderstorm-typical rains, particularly during the afternoon or evening. The distribution of rainfall during this period shows that the entire South-western sector at the hill country receives 250mm of rainfall, with the localized area on the south- western slops experiencing a rainfall in excess of 700mm(Keragala 771mm). Over most parts of the Island, the amount of rainfall varies from 100 to 250mm the notable exception being the Northern Jaffna Peninsula ( Jaffna-78mm, Elephant Pass -83mm).
2. Southwest Monsoon Season (May-September)
Windy weather during this monsoon eases off the warmth that prevailed during the 1st inter monsoon season. Southwest monsoon rains are experienced at any time during the day or night; sometimes occasionally mainly in the Southwestern port of the country. Amount of rainfall during this season varies from about 100mm over 3000mm. The highest rainfall received in the mid-elevations of the western slopes (Ginigathhena - 3267mm, Watawala - 3252mm, Norton - 3121mm). Rainfall decreases rapidly from these maximum regions towards the higher elevation, in Nuwaraeliya it drops to 853mm. The variation towards the Southwestern coastal area is less rapid, with the Southwestern coastal belt experiencing between 1000mm to 1600mm of rain during this five-month long period. The lowest figures are recorded from Northern and southeastern regions.
3. Second Inter-Monsoon Season (October-November)
Thunderstorm-type of rain, Particularly during the afternoon or evening, is the typical climate during this season. But unlike in the inter monsoon season, the influence of the weather system on the land with effects like depression and cyclones in the Bay of Bengal is common during the second inter monsoon season. Under such conditions, the whole country experiences winds with wide spread rain, sometimes leading to floods and landslides. second inter monsoon period which is from October-November is the most evenly balanced distribution of rainfall in Sri Lanka. Almost the entire island receives in excess of 400mm of rainfall during this season, with the Southwestern slops receiving higher rainfall in the range of 750mm to 1200mm.
4. Northeast Monsoon Season ( December - February)
The dry and cold wind blowing from the Indian land-mass will create a comparatively cool, but dry weather condition over many parts making the surrounding pleasant and comfortable weather except for coldness to a certain extent during the morning hours. Cloud-free skies provide days full of sunshine, and a pleasant and cool night. During this period, the highest rainfall figures are recorded in the North, Eastern slopes of the hill country and the Eastern slopes of the knuckles/Rangala Range. The maximum rainfall is experienced in the Kobonella estate (1281mm), and the minimum is in the Western coastal area around Puttalam (Chilaw - 177mm) during the same period.