Quick answer
In September the southwest monsoon weakens. Colombo averages roughly 200 to 250 mm of rain, more than in August, as afternoon storms return, and the sea on the west and south coasts stays rough for much of the month. The east coast and the north are mostly dry and calm, with Trincomalee averaging roughly 100 mm. The Cultural Triangle is hot and dry, with the first storms late in the month.
Key takeaways
- September is a transition month: the southwest monsoon fades and inter-monsoon storms start to form.
- Colombo's rainfall rises again from the August low, mostly in afternoon and evening storms.
- The southwest sea stays rough for much of the month and starts settling only late in September or October.
- The east coast is still mostly dry and calm, making it the safer beach choice.
- The Cultural Triangle is dry and hot, and the Minneriya elephant gathering is still strong early in the month.
September at a glance
September is the month the southwest monsoon loses its grip. The steady wind weakens and becomes less reliable, and the weather on the southwest side of the island shifts from monsoon showers to inter-monsoon storms: clearer mornings, building cloud and heavy rain in the afternoon or evening.
The rest of the island is still dry for most of the month. The east coast and the north have hot, windy days and calm seas, and the Cultural Triangle stays dry until the last week or so, when the first thunderstorms of the second inter-monsoon can roll in.
September is one of the least visited months, so the main reason to understand the weather is to find the parts of the island where it is still reliably good, which are mostly in the east.
- →West and south coasts: more storms, rough sea easing late.
- →Hill country: wet in the west, afternoon storms everywhere.
- →Cultural Triangle: dry, hot, first storms late.
- →East coast and north: mostly dry and calm.
The west and south coasts
Colombo averages roughly 200 to 250 mm of rain in September, more than in August, because afternoon thunderstorms return on top of the fading monsoon. Galle and Mirissa are similar. Mornings are often bright; the heavier rain comes later in the day.
The sea on the west and south coasts usually stays rough for much of September, with swell and currents. In some years it starts to settle in the second half of the month. Surfers find the south coast breaks still messy until October or November.
September is the quietest month on the south coast. Hotels are at low-season rates, and Galle Fort is almost free of crowds. A plan built around mornings out and afternoons indoors suits the weather.
The hill country
The western hills are still wet in September, with Nuwara Eliya averaging roughly 150 to 200 mm of rain, and afternoon storms become more common across the whole of the hill country. Mist is frequent in the afternoons. Daytime highs are about 19 to 20 °C in Nuwara Eliya.
Ella and Haputale are often bright in the mornings and cloudier later, with occasional storms. Kandy averages roughly 120 to 160 mm and has highs around 29 °C. Walks and viewpoints are best finished by early afternoon.
- →Nuwara Eliya: roughly 150 to 200 mm, misty afternoons.
- →Kandy: roughly 120 to 160 mm, about 29 °C.
- →Ella: bright mornings, cloud later.
The Cultural Triangle
The Cultural Triangle is mostly dry in September, with highs of about 33 °C. The tanks are at their lowest, and the Minneriya and Kaudulla elephant gathering continues, though it can disperse late in the month if early rains arrive.
The first storms of the second inter-monsoon can appear in the last week of September. They usually come in the late afternoon and are short. Mornings for climbing Sigiriya and Pidurangala are clear and slightly less hot than in August.
- →Highs about 33 °C, mostly dry.
- →Elephant gathering continuing.
- →First storms possible late in the month.
The east coast and the north
The east coast is still mostly dry in September. Trincomalee averages roughly 100 mm of rain, mostly in a few thunderstorms, and the sea at Nilaveli and Pasikudah is usually calm. Arugam Bay's surf season continues into October. Highs are around 33 °C.
The north is hot and dry, with Jaffna around 33 °C. Yala, in the southeast, usually closes for several weeks in roughly September and October, so wildlife plans in September often turn to Udawalawe, Wilpattu or Kumana instead.
- →Trincomalee: roughly 100 mm, mostly calm sea.
- →Arugam Bay: surf season continuing.
- →Yala: usually in its annual closure.
Planning around September weather
September suits travellers who want quiet roads and low prices and can accept some afternoon rain. A route through the Cultural Triangle, Kandy and Ella, then the east coast, uses the driest parts of the island.
The south coast is pleasant for sightseeing but not yet for swimming. Lankan Stays & Trails plans September trips with mornings for sightseeing, the east coast for beach time and an alternative safari park while Yala is closed.
Frequently asked questions
What is the weather like in Sri Lanka in September?
September is a transition month. The southwest monsoon fades, and afternoon thunderstorms become common on the west and south coasts and in the hills. The east coast and the north are mostly dry and calm, and the Cultural Triangle is hot and dry until the first storms late in the month.
How much does it rain in Colombo in September?
Colombo averages roughly 200 to 250 mm of rain in September, more than in August, because inter-monsoon thunderstorms add to the fading monsoon showers. Mornings are often bright and the heavier rain usually falls in the afternoon or evening.
Is September a good month for the east coast of Sri Lanka?
Yes, for most of the month. Trincomalee averages roughly 100 mm of rain, mostly in a few storms, and the sea at Nilaveli, Uppuveli and Pasikudah is usually calm. Arugam Bay's surf continues into October. The east coast is the best beach choice in September.
Can you swim on the south coast in September?
The sea on the south and west coasts usually stays rough for much of September, with swell and strong currents. In some years it begins to settle late in the month. Swimming should be judged daily with local advice; the east coast is the safer choice.
Is Yala open in September?
Yala usually closes for several weeks in roughly September and October for maintenance and to give the animals a rest during the driest period, but the exact dates change each year. Udawalawe, Wilpattu and Kumana are good alternatives while Yala is closed.
Is the Minneriya elephant gathering still on in September?
The gathering usually continues into September, when the tanks are at their lowest. If the second inter-monsoon rains arrive early, the elephants can start to disperse late in the month. Early to mid-September is generally a good time for afternoon safaris at Minneriya or Kaudulla.
How does Lankan Stays & Trails plan September trips?
September trips usually follow the driest parts of the island: the Cultural Triangle, Kandy, Ella and the east coast. Sightseeing is planned for mornings, and a safari park other than Yala is chosen while Yala is in its annual closure.