The highest day temperature in September 2025 was 88°F. The lowest night temperature was 80°F. The average values for day and night temperatures during September were 85.9°F и 81.8°F respectivly.

The average sea surface temperature in September 2025 for Dehiwala Mount Lavinia was 87.5°F. The maximum and minimum values were 86.2°F and 88.6°F respectively.

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

Precipitation total in September for Dehiwala Mount Lavinia is 12.7 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 10.4 mph. It makes September one of the most windy months of the year for Dehiwala Mount Lavinia.

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 Dehiwala Mount Lavinia in September is 4.9 hours.