September weather forecast
Kolkata, India

September marks the end of monsoon with a gradual decrease in the frequency of rains. Humidity remains high creating a somewhat uncomfortable atmosphere. However, festive preparations for the upcoming 'Durga Puja', the city's largest festival, are at its peak during September. The city is in full swing bustling with shopping and cultural activities. The rainfall gets reduced to 288mm (11.34"), showing signs of receding monsoon.

Temperature

September's onset brings an average high-temperature of a still hot 32.4°C (90.3°F), showing a minute difference from August's 32.1°C (89.8°F). Throughout the nights in September, an average low-temperature of 25.8°C (78.4°F) is noted.

Heat index

The heat index in September is evaluated at a blazing hot 46°C (114.8°F). Be alert: Heat exhaustion along with heat cramps are probable. Heatstroke is a threat with sustained physical activity.
Metrics for the heat index primarily focus on shaded spots and light wind conditions. Exposure to the direct sun might augment heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', blends air temperature and moisture content to represent the felt temperature to humans. An individual's perception of weather can be swayed by a variety of elements including metabolic differences, pregnancy status, and their level of physical exertion. It is noteworthy to mention that direct sunlight exposure can augment the felt temperature, leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to 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.
To cool down, the human body relies on perspiration, a process where excessive heat is eliminated as sweat evaporates. An upsurge in relative humidity affects normal body cooling mechanisms by slowing evaporation, hence reducing the rate at which the body cools and intensifying the perception of heat. Temperature imbalances caused by excessive heat retention can trigger heat-related maladies.

Humidity

In September, the average relative humidity is 81%.

Rainfall

In September, in Kolkata, the rain falls for 15.7 days. Throughout September, 288mm (11.34") of precipitation is accumulated. In Kolkata, India, during the entire year, the rain falls for 101.5 days and collects up to 1800mm (70.87") of precipitation.

Daylight

In September, the average length of the day is 12h and 17min.
On the first day of the month, sunrise is at 5:19 am and sunset at 5:53 pm. On the last day of September, in Kolkata, sunrise is at 5:27 am and sunset at 5:25 pm IST.

Sunshine

In Kolkata, the average sunshine in September is 3.9h.

UV index

In September, the average daily maximum UV index is 11. A UV Index reading of 11, and higher, represents an excessive health risk from exposure to the Sun's UV rays for the ordinary person.
Note: The daily high UV index of 11 during September translates into the following recommendations:
Take all necessary precautions, as unprotected skin can burn in minutes. Avoid direct exposure to the Sun between 10 a.m. and 4 p.m., the peak period for UV radiation, noting that objects like parasols or canopies might not offer complete sun protection. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Following every swim or outdoor workout, a sunscreen with an SPF of not less than 30 should be liberally applied and re-applied frequently, even on overcast days.