Monsoon winds start blowing in from the Indian Ocean and Bay of Bengal, creating heavy rainfall in the west and along the south coast. Av. monthly rainfall in the region is near to its peak, although you can still expect some dry days especially in the first half of the month.
Beach lovers generally turn their attention to the east coast with avg temp: 29 °C. Temperatures also remain high in the Cultural Triangle and rainfall is at a minimum (avg temp: 32 °C). To the south, Kandy and the hills of the Tea Country are expecting rainfall below their monthly average.
Unfollow the herd - travel in Sri Lanka during May and enjoy fewer crowds, better availability, and help to spread the economic benefits of tourism.
Swimming in the sea on Sri Lanka's south and west coasts during May is often not recommended and many hotels will have their red flags out to indicate that sea bathing can be dangerous at this time. That said, further up the west coast in Kalpitiya , the weather is expected to remain dry although the winds are picking up and the kite-surfing season is now well underway. On the other side of the mountains however, things are brightening up on the east coast (avg temp: 29 °C) now that the monsoon is over, so for R&R time in May and the best chance of sunshine, head to the east coast beaches.
Temperatures remain high in the Cultural Triangle and also Kandy (avg temp: 32 °C), with minimal rainfall. The Tea Country region also sees minimal rainfall and pleasant temperatures that hover around the mid-20°C's. May marks the end of the Adam's Peak pilgrimage season.
The south-west (the section south of Negombo & Colombo) and the entire south coast: Monsoon season.
The entire east coast: Peak season.
The central and northern section of the west coast (from Negombo northwards): Peak season.