SeasonMapMirissa weather in September
Sri Lanka
September in Mirissa: hot, soaked, with clean air — fine if you can take 27 rainy days.
#9 of 12 months in Mirissa · #812 of 1383 destinations to visit in September · comfort 76/100 (tier B)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Mirissa in September
Other months in Mirissa
Mirissa's forum calls February close to ideal — fewer crowds, good weather, and prime whale-watching season, which regulars say runs November through April. Sightings aren't guaranteed (recent reports put the odds around 50%), though dolphins show up far more reliably; tours head out around 6:45am, and regulars say the earliest departure gives the calmest seas and the best shot.
Add your own note from Mirissa's card on the map.
Mirissa climate normals — September
| Daytime high | 29°C / 84°F | 🥵 hot |
|---|---|---|
| Nighttime low | 25°C / 77°F | |
| Feels like (high) | 33°C / 91°F | |
| Sea temperature | 29°C / 83°F | ♨️ bath-warm |
| Rainfall | 191 mm / 7.5 in | ⛈ soaked |
| Rainy days | 27 days | |
| Humidity | 86% | 💦 very humid |
| Dew point | 24°C / 76°F | |
| Sunshine | 10 h/day | |
| Daylight | 12.1 h | |
| Wind | 22 km/h / 14 mph | |
| Air quality (US AQI) | 40 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Mirissa in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
BusyAugust break in Sri Lanka, school holidays in 3 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Mirissa's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherMirissa's weather peaks January–March, best around February.
Best weatherFair weatherToughest weather
What's on in Mirissa in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
Southwest (Yala) monsoon
15 May – 15 Sep · usuallyRiskThe whale boats stop, the bay picks up a heavy shore break and the sand narrows to a strip. Half the beach places board up; the ones that stay open charge a third of the winter rate.
Nearby, and something's on
Within 300 km of Mirissa — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Mirissa?
Mirissa in September — FAQ
- Is September a good time to visit Mirissa?
- September in Mirissa: hot, soaked, with clean air — fine if you can take 27 rainy days. It ranks #9 of 12 months for Mirissa on SeasonMap's comfort score (76/100).
- What is the weather like in Mirissa in September?
- In September, Mirissa averages a daily high of 29.1°C and a low of 25°C, with about 191.4 mm of rain over roughly 26.5 rainy days.
- What is the air quality in Mirissa in September?
- Mirissa has a mean US Air Quality Index of about 40 in September.
Other months in Mirissa
Compare Mirissa in September
Warmer or cooler than Mirissa in September
Similar destinations in South Asia — September
Within 300 km: Sigiriya's The Gathering at Minneriya around 15 Jul – 30 Sep, and Colombo's East coast season around 1 May – 30 Sep.