The highest day temperature in September 2025 was 88°F. The lowest night temperature was 82°F. The average values for day and night temperatures during September were 85.7°F и 82.1°F respectivly.

The average sea surface temperature in September 2025 for Negombo was 87.3°F. The maximum and minimum values were 85.8°F and 88.2°F respectively.

Most of the days in September are gloomy but you can also expect sunny days.

Precipitation total in September for Negombo is 9.7 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 11.8 mph. It makes September one of the most windy months of the year for Negombo.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Negombo in September is 5.0 hours.