December weather forecast and climate
Mumbai, India

The first month of the winter, December, is also a hot month in Mumbai, India, with average temperature fluctuating between 18.6°C (65.5°F) and 32°C (89.6°F).
The ideal sea water temperature of 27°C (80.6°F) and only 0.4 rainfall days, with 5.3mm (0.21") of accumulated rainfall, makes December the best time for swimming and other water activities.

Temperature

In December, the average high-temperature is practically the same as in November - a still hot 32°C (89.6°F). In Mumbai, in December, the average low-temperature is 18.6°C (65.5°F).

Heat index

The average heat index is calculated to be an extremely hot 40°C (104°F). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'feels like', 'real feel', or 'apparent temperature', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (clothing, differences in body mass, height, and shape, metabolic differences). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
The human body cools itself through perspiration, as excessive warmth is removed from the body through sweat evaporation. With a lot of moisture in the air, the evaporation process is not as effective, and the body does not cool down as efficiently, creating a perception of overheating. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 37.5°C (99.5°F) to 38.3°C (100.9°F), thermal conditions are potentially life-threatening.

Humidity

In Mumbai, India, the average relative humidity is 69%.

Rainfall

In December, the rain falls for 0.4 days. Throughout December, 5.3mm (0.21") of precipitation is accumulated. Throughout the year, there are 78.9 rainfall days, and 2258mm (88.9") of precipitation is accumulated.

Sea temperature

In December, the average sea temperature is 27°C (80.6°F).
Note: Water temperature between 25°C (77°F) and 29°C (84.2°F) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

Daylight

December has the shortest days of the year in Mumbai, with an average of 11h of daylight.

Sunshine

The average sunshine in Mumbai is 8.2h.

UV index

The month with the lowest UV index is December, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health hazard from the exposure to the Sun's UV radiation for the average person.
Note: The daily maximum UV index of 7 interpret into the following advice:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.