Sri Lanka Monsoon Seasons: Wet Coast, Dry Coast

How do Sri Lanka's monsoons work, and what do they mean for a route?

Quick answer: Sri Lanka has two monsoons, and the central mountains split the island between them. The south-west monsoon, May to September, soaks the south-west coast and the hills while the east and north stay dry. The north-east monsoon, December to February, flips that, and the wettest month at every station we checked falls between October and December. So when the coast you planned is wet, you can usually move to the other side of the island.

This page explains the cause and the rerouting. For which month suits which coast, use our best time to visit Sri Lanka guide, which goes month by month. This guide stays on the mechanism and what to do when the weather does not match your plan.

What are the four seasons?

Wikipedia's geography entry adds the wind detail. From mid-May to October, south-west winds carry moisture from the Indian Ocean, and the rain falls on the south-west and the slopes of the Central Highlands. From December to March the north-east monsoon blows from the Bay of Bengal. March to mid-May brings light variable winds and evening thundershowers. In October and November, squalls and sometimes cyclones bring rain to the south-west, north-east and east.

Why do the mountains split the island into wet and dry?

The central southern highlands rise above 2.5 km, and Sri Lanka Tourism says their ridges, peaks and valleys strongly influence winds, seasonal rain, temperature and humidity. Wikipedia describes the result as a wet zone in the south-west and the mountains, with about 2,500 mm of rain a year, and a dry zone with 1,200 to 1,900 mm a year. In the south-west monsoon, the leeward slopes in the east and north-east get little rain.

You can see the split in the station data. The table shows each station's wettest and driest months in the WMO 1991 to 2020 normals.

Three things stand out. The south-west coast has a second peak in May. The east and north peak in November to December and fall almost dry in June and July. And the single wettest month at every station falls between October and December, which is why the second inter-monsoon, and the start of the north-east monsoon, is the hardest time to find a dry coast. Our Sri Lanka in October guide has more on that month.

What do the monsoons do to roads, trains and the sea?

Hill roads and trains. Heavy rain brings landslide risk in the hills. The National Building Research Organisation issues landslide warnings, which the Disaster Management Centre publishes. Our Kandy to Ella by road guide says to check the latest warning before you travel and avoid hill roads in heavy rain. The Upcountry railway line was badly damaged by Cyclone Ditwah in late 2025, and our Colombo to Kandy train guide tracks which sections have reopened.

The sea. Sri Lanka Tourism says seas can be rough in October and November, and calls December to February the time of calm seas on the south-west coast. Boat trips can be cancelled in rough weather. The Sri Lanka Navy lists southern whale-watching cruises from Galle for November to April and Trincomalee cruises for May to October, as quoted in our whale watching guide and monthly guides. Sightings are never guaranteed.

The ferry. Our getting around guide says the Nagapattinam to Kankesanthurai passenger ferry pauses for the north-east monsoon, as it did in 2025. See the India to Sri Lanka ferry guide for the checked details.

Flights. We found no source on monsoon effects on flights, so we make no claim. Check airline notices.

What do you do when the wrong coast is wet?

Use the season to pick the side of the island, then check the forecast for the exact stops.

Our east versus south coast guide says season is only a first filter: a monsoon label cannot guarantee dry weather, calm water, visibility or a departing boat.

What is the weather situation this week?

This section is time-sensitive and was checked on 24 October 2026. The Department of Meteorology said on 23 October that rain would continue in the south-west until 27 October. A low pressure area over the Bay of Bengal near the North Andaman Islands was forecast to become a cyclonic storm by 26 October, and it was not expected to hit Sri Lanka directly (Colombo Tribune, 23 October 2026). Trains between Rambukkana, Peradeniya and Gampola are suspended on 24 and 25 October after a landslide at Kadigamuwa, with refunds for reserved seats. On the evening of 25 October 2026 the Railways Department extended the suspension: all trains between Rambukkana, Peradeniya and Gampola are off from midnight at the end of 25 October until further notice, with no restart date given (Newswire, 25 October 2026, Daily Mirror, 25 October 2026). A National Building Research Organisation landslide warning issued at 4 pm on 23 October was valid to 4 pm on 24 October.

We found no source on whether this affects sea trips, so check with the operator and the Navy's whale-watching site. Late October falls in the second inter-monsoon.

A simple rerouting checklist

This is practical advice, not an official rule.

• Pick the dry side first. Use the table above to choose a coast, then book the flexible parts.
• Book refundable stays. In October and November, keep spare nights.
• Keep one indoor option per day. Museums, temples and cafes are useful in a shower.
• Check three notices: the Department of Meteorology forecast, the National Building Research Organisation landslide warning, and the rail notice for any train you plan to use.
• Do sea and hill days early. We have no sourced hourly data, so treat this as general caution.
• Do not bank on a boat. Sea trips are cancelled in rough weather.

What this page does not cover

• Month by month weather: see the best time to visit guide.
• Specific hotels, boats or tour operators.
• Flight delays or insurance claims. Read your own policy.
• Rain forecasts beyond the Department of Meteorology notices cited above.