Climate averages 1991–2020
Negombo weather
in September.
A hot, very wet month: the 10th warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Negombo: daytime highs average 28.6°C and nights cool to about 24.9°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 215 mm of rain on roughly 25 days, which makes September a very wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 10 min on an average September day.
The nearest other city in this atlas is Colombo (30 km away). In September its highs average 28.5°C, about as warm as Negombo, with 223 mm of rain.
Among the 12 cities listed in Sri Lanka, Negombo ranks 7th of 12 for the warmest September highs and 9th of 12 for the driest September (rainfall, lowest first). The mean September high of those 12 cities is 29.9°C; Negombo is 1.3°C cooler than that mean.
From September to October, average highs rise by 0.2°C to 28.8°C, and monthly rainfall rises from 215 mm to 315 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Negombo climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 30.2°C23.2°C | 23.2°C | 38 | 6.2 | 11.812 h |
| February | 31.8°C23.7°C | 23.7°C | 40 | 6.5 | 11.912 h |
| March | 31.8°C24.8°C | 24.8°C | 76 | 15.8 | 12.112 h |
| April | 30.7°C25.5°C | 25.5°C | 163 | 26.0 | 12.312 h |
| May | 29.6°C25.7°C | 25.7°C | 255 | 28.6 | 12.412 h |
| June | 28.8°C25.4°C | 25.4°C | 224 | 27.0 | 12.513 h |
| July | 28.5°C25.2°C | 25.2°C | 176 | 24.5 | 12.512 h |
| August | 28.4°C25.0°C | 25.0°C | 165 | 23.9 | 12.412 h |
| September, selected | 28.6°C24.9°C | 24.9°C | 215 | 25.3 | 12.212 h |
| October | 28.8°C24.5°C | 24.5°C | 315 | 26.4 | 12.012 h |
| November | 29.0°C24.0°C | 24.0°C | 271 | 22.3 | 11.812 h |
| December | 29.1°C23.5°C | 23.5°C | 137 | 14.1 | 11.712 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Colombo in SeptemberSri Lanka · 30 kmHigh 28.5°C · Low 24.5°C · 223 mm rain
- Dehiwala-Mount Lavinia in SeptemberSri Lanka · 41 kmHigh 28.2°C · Low 24.5°C · 232 mm rain
- Kandy in SeptemberSri Lanka · 88 kmHigh 27.1°C · Low 21.0°C · 121 mm rain
- Galle in SeptemberSri Lanka · 136 kmHigh 27.7°C · Low 24.7°C · 240 mm rain
- Matara in SeptemberSri Lanka · 160 kmHigh 28.2°C · Low 24.6°C · 196 mm rain
- Ambalantota in SeptemberSri Lanka · 178 kmHigh 30.9°C · Low 25.1°C · 87 mm rain
- Batticaloa in SeptemberSri Lanka · 212 kmHigh 33.2°C · Low 25.6°C · 48 mm rain
- Trincomalee in SeptemberSri Lanka · 216 kmHigh 33.0°C · Low 25.8°C · 65 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Negombo) is explained once on the Negombo year overview and on the Sources, method and limits page.