September weather forecast
Mumbai, India

September in Mumbai sees a definite decline in the monsoon activity. The rainfall further declines to 312mm (12.28"), and temperatures begin to climb back up, with highs around 30.4°C (86.7°F). Most of the city starts to dry up and regain its pre-monsoon charm. Outdoor activities gradually become enjoyable again during the later part of the day. As September ends, the temperatures start to rise, indicating the fading monsoon and the city's gradual return to warm, pleasant weather.

Temperature

The transition from August to September sees average high-temperatures adjusting to a hot 30.4°C (86.7°F), from a not significantly different 29.6°C (85.3°F). During the month of September, an average low-temperature of 24.3°C (75.7°F) is recorded in Mumbai.

Heat index

For September, the heat index is appraised at an extremely hot 40°C (104°F). Heightened precautions are necessary, heat cramps and heat exhaustion are potential risks. Continuous activity could lead to heatstroke.
Keep in mind the heat index values are meant for areas in shade and with light wind. Being exposed to direct sunshine might trigger a heat index increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is a composite of temperature and humidity figures to convey how warm it feels. The influence of weather is personal, differing among a variety of individuals based on differences in body mass, stature, and the level of physical activity. Direct sun rays can make one feel hotter, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Children often fail to recognize the requirement to rest and rehydrate. Thirst, being a late symptom of dehydration, underlines the importance of maintaining hydration, especially during ongoing physical activities.
The physiological response of the human body to excess warmth is to perspire, thereby cooling itself through sweat evaporation. When air moisture content is high, the cooling process through evaporation is not as efficient, leading to an ineffective body cooling process and a feeling of overheating. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

In Mumbai, the average relative humidity in September is 83%.

Rainfall

In Mumbai, India, during September, the rain falls for 14.4 days and regularly aggregates up to 312mm (12.28") of precipitation. In Mumbai, during the entire year, the rain falls for 78.9 days and collects up to 2258mm (88.9") of precipitation.

Sea temperature

In Mumbai, the average seawater temperature in September is 28.7°C (83.7°F).
Note: For swimming, diving, or other water activities, temperatures from 25°C (77°F) to 29°C (84.2°F) provide the most enjoyable experience for extended periods without discomfort.

Daylight

In September, the average length of the day in Mumbai is 12h and 15min.
On the first day of the month, sunrise is at 6:23 am and sunset at 6:53 pm. On the last day of September, in Mumbai, India, sunrise is at 6:28 am and sunset at 6:27 pm IST.

Sunshine

The average sunshine in September is 5.5h.

UV index

March through September, with an average maximum UV index of 12, are months with the highest UV index in Mumbai. A UV Index estimate of 11, and higher, represents an extreme health hazard from exposure to the Sun's UV rays for the ordinary person.
Note: The maximum UV index, 12 during September, leads to the following recommendations:
Take every essential safety procedure. Individuals with fair skin could sustain burns in less than 5 minutes. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is at its strongest, and remember that parasols or canopies do not offer full protection. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Broad-spectrum sunscreen with an SPF of 30 or more should be applied liberally every two hours and directly after outdoor activities or swimming. Be careful! The Sun's UV radiation is accentuated by reflecting off sand and water.