September weather forecast
Negombo, Sri Lanka

September marks the transition towards the end of the rainy season in Negombo, Sri Lanka. Slight fluctuations in temperature and rainfall can be observed compared to August. The sea temperature starts to rise, making water activities more enjoyable. Wind speeds decrease and create welcoming and more relaxed conditions. Additionally, the city's visual appeal is enhanced with clear skies and longer daylight hours.

Temperature

With the transition into September, Negombo notes an average high-temperature of a still moderately hot 29.5°C (85.1°F), closely resembling August. September notes an average low temperature of 25.2°C (77.4°F), subtly down from the daytime highs.

Heat index

September's heat index is computed to be a sweltering 36°C (96.8°F). Greater preventive actions are needed, heat exhaustion and heat cramps are likely. Persistent activity could provoke heatstroke.
Note that heat index values are valued for light wind and location in the shade. Uninterrupted exposure to the sun may boost the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', is a value derived by merging air temperature with the humidity to convey how the climate feels. The individual's experience of temperature can be shaped by numerous aspects such as metabolic variations, physical exertion, and attire. Being under direct sunshine can magnify the heat experience, possibly pushing up the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Typically, children face more danger than adults as they usually perspire less. Their larger skin surface relative to their small bodies and increased heat output from their activities enhance their risk.
The body's innate mechanism to counteract overheating is through perspiration, as it leverages the cooling effects of sweat evaporation. When the level of relative humidity is elevated, evaporation diminishes, causing more warmth to be retained in the body than in dry air. Potential thermal conditions emerge as the body's heat gain outpaces its cooling mechanisms.

Humidity

The average relative humidity in September in Negombo is 81%.

Rainfall

In Negombo, in September, during 24.4 rainfall days, 153mm (6.02") of precipitation is typically accumulated. In Negombo, Sri Lanka, during the entire year, the rain falls for 265.4 days and collects up to 1744mm (68.66") of precipitation.

Sea temperature

In Negombo, in September, the average water temperature is 27.6°C (81.7°F).
Note: Water activities in surface temperatures between 25°C (77°F) and 29°C (84.2°F) are seen as exceptional and extremely agreeable for lengthened time spans.

Daylight

The average length of the day in September in Negombo is 12h and 10min.
On the first day of the month, sunrise is at 06:03 and sunset at 18:18. On the last day of September, in Negombo, sunrise is at 05:58 and sunset at 18:02 +0530.

Sunshine

In Negombo, the average sunshine in September is 7.7h.

UV index

The months with the highest UV index are January through April, July, September, November and December, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: In September, a regular UV index of 7 translates into these guidelines:
Escape overexposure. People with light skin may incur burns in fewer than 20 minutes. The time between 10 a.m. and 4 p.m. is when UV radiation is at its peak. Limit exposure to direct sunlight during these hours. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage. Be mindful! Sand and water reflections can up the Sun's UV exposure.