Dehiwala Weather in September

Thinking of visiting Dehiwala in September? Expect very high temperatures reaching 30°C (86°F) during the day, dropping to 25°C (77°F) at night. Heavy showers are common during the rainy season.

Rainfall in Dehiwala in September

As part of the rainy season, Dehiwala sees around 14 days of rain in September, with an average of 263 mm (10 in). With high rainfall totals spread across the month, individual showers can be very heavy. Waterproof gear is strongly recommended.

Temperature in Dehiwala in September

Daytime temperatures in Dehiwala reach 30°C (86°F) in September, dropping to 25°C (77°F) at night. If you're spending a lot of time outdoors, it helps to plan around the warmer part of the day. At 25°C (77°F) overnight, it stays warm after dark. Light, breathable clothing and good airflow in your room make a noticeable difference.

Sunshine in Dehiwala in September

The city usually sees around 189 hours of sunlight, indicating a moderately sunny period (despite it being part of rainy season).

Wind Speed in Dehiwala in September

September sees wind speeds averaging 2 m/s (4 knots). You'll typically experience pleasant light breezes that move leaves slightly and feel refreshing. As an average, expect variation from very calm days to periods with more apparent air movement.

Average water temperature in September

The water is 28°C (82°F) this month — warm enough that getting in requires no effort at all. Good conditions for swimming, snorkeling, or just floating around.

September in Dehiwala can still be great, but if you prefer pleasant temperatures along with dry and sunny conditions, our weather planner can help you explore other options in the world.

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For a detailed overview over the year and the best time to visit Sri Lanka, check out our Dehiwala's climate page.

Dehiwala Temperature in September

Min Temperature 25°C (77°F)  

Max Temperature 30°C (86°F)  

Water Temperature 28°C (82°F) *  

Chance of Rain 45%  

Precipitation 263 mm (10 in)  

Rainy days 14 days  

Humidity 76% *  

Windspeed 2 m/s (4 knots) *  

Sunshine 189 hours *  

Percentage Sunshine *  

* Data from: Colombo, Sri Lanka (5 KM, 3 Miles).

Daily Historical Temperatures

46-year average (1976-2025)

Based on our historical records, temperatures in Dehiwala typically stay consistent throughout September, with daily highs averaging around 30°C (86°F). Nights are warm, with lows around 26°C (79°F).

Average temperatures in September

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Daily Historical Precipitation

46-year average (1976-2025)

Average daily rainfall for each day of the month based on long-term records.

Average precipitation in September

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

‹ January February March April May June July August September October November December ›

Historical weather for Dehiwala in September

Browse day-by-day weather records for Dehiwala spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

Historical weather Temperatures Precipitation

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‹ January February March April May June July August September October November December ›

Dehiwala historical weather extremes in September

Based on 27 years of weather observations in Dehiwala between 1998 and 2025, these are the recorded extremes.

• The warmest day in September was on September 28, 2024, with a maximum of 34°C (93°F).
• Dehiwala experienced its chilliest September day on September 24, 2000, reaching only 25°C (77°F).
• The lowest overnight temperature recorded in September was 22°C (72°F) (September 9, 2007).

What to Wear in Dehiwala in September

Warm weather calls for comfortable, breathable clothing in September. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). Also bring a poncho, it will rain a lot! Waterproof everything you can. The water temperature sits at about 28°C (82°F), making it perfect for swimming and water activities. Don't forget to pack your favorite swimwear and perhaps some snorkel gear. It won't hurt to bring your sunglasses along, as you'll see some sunny periods.

What To Do in Dehiwala in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

7/10

Cycling

7/10

Walking

7/10

Camping

7/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Sri Lanka, check out our Dehiwala's climate page.

More climate data for Dehiwala

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Dehiwala climate overview or explore weather in Sri Lanka.