West coast and south
This region, which stretches from Colombo to the southern tip of the island, has a generally warm and humid climate. It is sunny from November to March, with pleasant temperatures (27° on average), which is the best time to discover this region. On the coasts, the heat is rarely overwhelming, as it is tempered by ocean winds. From April onwards, light rains begin to fall sporadically, and temperatures and humidity levels rise. Days are sunny, but the sky tends to darken in the late afternoon. The summer monsoon settles in from late May to early September. It's often sunny in the morning, but heavy rain can fall at any time of day. However, it rains less on the coast from Negombo to Jaffna, as this part of the island is partially sheltered from the winds by the southern tip of India. Particular caution is advised when swimming at this time of year, as strong winds blow and the ocean is rough and therefore dangerous. Colombo's climate is hot and humid all year round (70% humidity, with peaks of up to 90% during the monsoon season).
Best time to visit the west coast and south: December to March.
North and east coast
To get an idea of this region, imagine a line running from Jaffna to Arugam Bay, which divides the island into two distinct parts. This region is more arid than the rest of the country, and from April to September it enjoys a hot, dry season, with high levels of sunshine. The mountains in the center and south protect these coasts from the great summer monsoon. Temperatures then frequently exceed 30°. This is the ideal time to discover the superb beaches of the east coast. In October and November, the climate remains more or less the same, with only a slight increase in humidity. The population of these regions eagerly awaits the light monsoon, which usually arrives in December and lasts until March. In recent years, however, it has been noted that this monsoon has diminished in intensity, becoming insignificant or even absent in some years. As the east coast is renowned for its surfing spots, you can deduce that the winds can sometimes blow violently and the currents can be powerful. Caution is therefore advised when swimming, all year round.
Best time to visit the north and east coasts: May to September.
Mountainous regions
Altitude strongly influences the climate in the highlands and mountains of the south, which is much milder than in the plains and along the coast. The mountainous regions are the wettest parts of the country. Nights are cool and showers frequent. The great monsoon, from May to September, falls on the mountains to the west of the island, so temperatures can sometimes drop below 10° in certain climate stations, such as Nuwara Eliya and Ella. Heavy rainfall can cause flooding and landslides. The winds of the minor monsoon, from December to March, change the climate in the mountainous regions to the east, but rainfall remains sporadic. Whatever the season, rain can come at any time. So bring warm clothes, a windbreaker and an umbrella!
Best time to visit the mountain regions: November to March in the west, year-round in the east.
Cyclones
In addition to its two monsoons, Sri Lanka is also subject to tropical cyclones, which usually sweep the country in November and December. Their intensity is variable but they can bring sudden and heavy rainfall and strong winds. From October to November and from January to March, thunderstorms can occur at any time because during these periods the ocean is warm and contributes to the formation of lows. It is therefore difficult to predict exactly when the rains will hit the island. In general, these events remain sporadic and last only a short time. During the summer monsoon, some areas of the country, especially in the central part of the island and in the mountainous regions, can experience floods. These floods sometimes cause landslides that hit the local population hard. If you are traveling to Sri Lanka during this period, it is imperative to check the weather forecast beforehand and to follow the country's news.
