Sri Lanka's two monsoons explained: why there is always a sunny coast

People often ask us when the monsoon is in Sri Lanka. The honest answer is that there are two, and they take turns.

For a small island, Sri Lanka has a surprisingly split climate. One monsoon blows in from the southwest in the middle of the year and soaks the west and south. The other arrives from the northeast around the turn of the year and brings rain to the north and east. Between them sit two shorter, unsettled spells when the winds change over.

The result is a country where one coast is usually in season while the other is not. Plan with that in mind, and Sri Lanka works in far more months than most people assume.

The shape of the year

Sri Lanka's tourism board divides the year into four seasons, and it is the simplest way to understand it.

• Southwest monsoon, May to September. Heavy rain on the southwest coast and in the hills. The dry zone of the north and east, including Trincomalee, Arugam Bay and Jaffna, is at its best.
• Northeast monsoon, December to February. The peak season on the southwest coast, with clear skies and calm seas. The north and east are wetter.
• First inter-monsoon, March and April. A transition, warm and humid, with afternoon thunderstorms. A good time for the ancient cities and the hill country.
• Second inter-monsoon, October and November. Showers across much of the island, sometimes heavy.

What the rainfall figures show

The long-term averages that Sri Lanka's Department of Meteorology reports through the World Meteorological Organization make the pattern plain.

On the west coast, Colombo averages under 75mm of rain in January and February. In May it averages close to 400mm, and it is wetter still in November, when the second inter-monsoon adds its own heavy showers.

On the south coast, Galle follows the same shape. January and February are the driest months, while May and October to November are the wettest.

On the east coast, the picture is reversed. At Trincomalee, June is the driest month of the year, with only about 25mm of rain, and May to August are all dry. Then November and December bring well over 300mm a month. Batticaloa, further south on the same coast, is similar, with December its wettest month.

Temperature barely changes along the coasts, with daily highs of around 28 to 35°C through the year. The east coast is at its hottest in its dry season, when Trincomalee averages about 34°C.

In the hill country, Nuwara Eliya is much cooler, with highs of about 19 to 23°C, and gets some rain in most months. It is noticeably drier from January to March.

Which coast in which month

December to March: the south and west

This is Sri Lanka's classic season, and the time most people go. The beaches of the south coast, from Bentota round to Tangalle, are at their best, and Galle's old fort is lovely to walk in the dry, bright weather. The sea is calm and good for swimming.

The tourism board also flags this as the season for whale watching off the southwest coast. Boats go out from the south coast in the calm early mornings, weather permitting.

It is also the ideal time to combine the beaches with the Cultural Triangle, the region of ancient capitals and rock temples in the north-central plains, and with the tea country around the hills.

Caveat: this is the busiest period, especially around Christmas and New Year. Book the best beach hotels early. December can still be showery at the start of the month, and the east coast is out of season.

April: the changeover

April is warm and humid, and the afternoons can bring thunderstorms. It is still a good month for the hill country and the ancient cities, and the south coast is often fine. Sinhala and Tamil New Year falls in mid-April.

May to September: the east

As the southwest monsoon brings rain to the west, the east coast comes into its own. Trincomalee and the beaches north of it, Nilaveli and Uppuveli, have calm seas and long dry spells. Further south, Arugam Bay is best known for its surf in these months, and Pasikudah has a long, shallow beach.

The Cultural Triangle stays mostly dry through the middle of the year too; Anuradhapura averages under 40mm a month from June to August, so an east coast trip combines well with the ancient sites. The hills are wetter and cloudier but still worth a night or two, and the tea estates are green.

Caveat: the east coast is quieter and has fewer high-end hotels than the south. The southwest beaches are wet and the sea is too rough for comfortable swimming at many of them.

October and November: the in-between

This is the hardest time to call. The second inter-monsoon brings showers across much of the island, and some of the heaviest rainfall of the year falls on the west and in the hills. It is rarely rain all day; more often it is heavy downpours in the afternoon with sunny mornings.

We would still travel in October and November for the right trip, particularly one focused on the ancient cities, wildlife and the hills, where the landscape is at its greenest. We would not pick them for a beach-first holiday.

Why the hills are different

The hill country sits in the middle of the island, rising to over 2,000m. It catches rain from both monsoons, which is why it is green all year and why the tea grows so well. It is also why the weather there changes quickly. A clear morning can turn misty by lunchtime.

For the classic hill country experiences, the train between Kandy and Ella, a stay on a working tea estate, and walks to viewpoints, aim for January to April when the chances of clear mornings are highest.

What monsoon rain is really like

It helps to know what a wet month means in practice. Monsoon rain in Sri Lanka rarely settles in grey for days at a time, as a British summer can. More often there is a heavy downpour, sometimes spectacular, followed by sunshine and steam rising off the roads.

That matters for planning. A wet month on one coast is poor for a beach holiday, because the sea turns rough and murky and the flags go up on the beaches. It is much less of a problem for touring, where an afternoon storm is simply a good excuse for a long lunch or a rest before dinner.

The bigger risk is travel time. Heavy rain slows the roads, and in the hills it can bring landslips that close a route for a day. We build in slack on wet-season itineraries for exactly that reason.

What to pack for two climates

Almost every trip crosses at least two climates. The coasts are hot and humid all year, so pack light cotton and linen, good sun protection and a hat. The hills are cooler, especially at night in Nuwara Eliya, so bring a warm layer and a light waterproof. The FCDO advises covering legs and shoulders and removing shoes and hats in Buddhist temples, so a scarf or sarong is useful to carry every day.

How we would plan it

A winter trip

Two or three nights in the Cultural Triangle, two nights in the hills, then a week on the south coast. This works from late December to March and is the classic Sri Lanka itinerary.

A summer trip

The Cultural Triangle, then the east coast for the beach, with a night or two in the hills if you want the cooler air. This works from May to September, and in the school holidays it is a good alternative to the more expensive Mediterranean weeks.

An autumn trip

Wildlife, culture and the hills, with a beach finish in the Maldives rather than Sri Lanka. The two are a short flight apart.

Getting there

SriLankan Airlines flies direct from London to Colombo in about ten and three-quarter hours.

Most trips begin with a drive, either south to the coast or north to the ancient cities. Road journeys take longer than the distances suggest, so we plan routes with no more than three or four hours in a car on any one day.

The short version

• Beach holiday in winter: the south and west coasts, December to March.
• Beach holiday in summer: the east coast, May to September.
• Culture and the hills: January to April is the best of it, but the ancient cities work in most months.
• Autumn: fine for culture and wildlife, less so for beaches.

Browse our beach escapes and culture and heritage ideas, or talk to us about which side of the island suits your dates.