SeasonMapSylhet weather in September
Bangladesh
September in Sylhet: sweltering, soaked, with muggy air — not the time — 26 rainy days.
#9 of 12 months in Sylhet · #1301 of 1383 destinations to visit in September · comfort 41/100 (tier F)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Sylhet in September
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Sylhet climate normals — September
| Daytime high | 31°C / 88°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 25°C / 77°F | |
| Feels like (high) | 38°C / 100°F | |
| Rainfall | 456 mm / 18 in | ⛈ soaked |
| Rainy days | 26 days | |
| Humidity | 87% | 💦 very humid |
| Dew point | 25°C / 77°F | |
| Sunshine | 7.3 h/day | |
| Daylight | 12.3 h | |
| Wind | 7 km/h / 4 mph | |
| Air quality (US AQI) | 76 | 🙂 moderate |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Sylhet 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.
Shoulder seasonschool holidays in 3 of the markets that fill it, an ordinary month(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Sylhet'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 weatherSylhet's weather peaks December–February, best around January.
Best weatherFair weatherToughest weather
What's on in Sylhet in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Hazard
Flash-flood season
15 May – 30 Sep · usuallyClosuresThe Surma and Kushiyara rivers regularly burst their banks between May and September: the 2022 flood submerged most of Sylhet and neighbouring Sunamganj district, shut the airport and railway station, and displaced close to half a million people. Smaller flash floods recur most years. Source ↗
- Nature
Ratargul submerged
1 Jun – 30 Sep · usuallyMonsoonBangladesh's only freshwater swamp forest floods to 15-20 feet during the monsoon, turning the trees into a paddled maze reachable only by small wooden boat. Outside these four months the water drops and much of the forest floor is walkable clay. Source ↗
- Season
Wet season
MonsoonRisk26 rainy days and about 456 mm in the month — the real kind of rainy season, not afternoon showers.
from the climate normals
Where is Sylhet?
Sylhet in September — FAQ
- Is September a good time to visit Sylhet?
- September in Sylhet: sweltering, soaked, with muggy air — not the time — 26 rainy days. It ranks #9 of 12 months for Sylhet on SeasonMap's comfort score (41/100).
- What is the weather like in Sylhet in September?
- In September, Sylhet averages a daily high of 30.9°C and a low of 25.2°C, with about 456.3 mm of rain over roughly 26.3 rainy days.
- What is the air quality in Sylhet in September?
- Sylhet has a mean US Air Quality Index of about 76 in September.