September weather forecast and climate
Cozumel, Mexico

Palm trees and clear blue waters on Chen Rio white sandy beach in Cozumel, Mexico
Palm trees and clear blue waters on Chen Rio white sandy beach in Cozumel, Mexico

Weather in September

September, the first month of the autumn, in Cozumel, is still a hot month, with average temperature ranging between max 31.9°C (89.4°F) and min 23.6°C (74.5°F).

Temperature

In Cozumel, Mexico, the average high-temperature is almost the same as in August - a still tropical 31.9°C (89.4°F). In Cozumel, the average low-temperature is 23.6°C (74.5°F).

Heat index

The average heat index in September is estimated at a blazing hot 47.1°C (116.8°F). Beware - heat cramps and heat exhaustion are very likely. Heatstroke is imminent with prolonged activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'real feel', 'feels like', or 'apparent temperature', combines air temperature and relative humidity to represent a human perceived temperature equivalent. This effect is individual, with diverse people perceiving weather differently for numerous reasons (pregnancy, clothing, wind), and activity. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
Perspiration is the human body's physiological response to high temperatures and is an attempt to lower body temperature through evaporation of sweat. 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. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

September is the most humid month, with an average relative humidity of 87%.

Rainfall

In Cozumel, during September, the rain falls for 15.4 days and regularly aggregates up to 240.2mm (9.46") of precipitation. In Cozumel, Mexico, during the entire year, the rain falls for 119.9 days and collects up to 1489.9mm (58.66") of precipitation.

Sea temperature

July through October, with an average sea temperature of 29°C (84.2°F), are months with the warmest seawater in Cozumel.
Note: For any water activity, surface water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered as excellent and extremely pleasant for lengthened periods.

Daylight

In Cozumel, Mexico, the average length of the day is 12.2h.

Sunshine

Months with the least sunshine are September and November, with an average of 6.1h of sunshine.

UV index

The average daily maximum UV index in September is 11. A UV Index reading of 11, and higher, represents an ultimate health vulnerability from unprotected exposure to the Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 11 translate into the following recommendations:
Take all necessary precautions, as unprotected skin can burn in minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. 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. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.
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FAQ

What is the temperature in September in Cozumel?

In Cozumel, in September, the average high-temperature is 31.9°C (89.4°F), and the average low-temperature is 23.6°C (74.5°F). The average heat index (a.k.a. 'felt air temperature', 'feels like'), that combines relative humidity and air temperature, in September is estimated at 47.1°C (116.8°F).

What is the most humid month in Cozumel?

September is the most humid month, with an average relative humidity of 87%.

What is the average humidity in September in Cozumel?

In September, the average relative humidity in Cozumel is 87%.

How many days does it rain in September in Cozumel?

In Cozumel, Mexico, during September, the rain falls for 15.4 days and regularly aggregates up to 240.2mm (9.46") of precipitation.

What months are the sea warmest in Cozumel?

July through October, with an average sea temperature of 29°C (84.2°F), are months with the warmest seawater in Cozumel.

What is the sea water temperature in September in Cozumel?

In Cozumel, Mexico, in September, the average water temperature is 29°C (84.2°F). For any water activity, surface water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered as excellent and extremely pleasant for lengthened periods.

How many hours of daylight does Cozumel have in September?

The average length of the day in September in Cozumel is 12.2h.

What is the month with the least sunshine in Cozumel?

September and November, with an average of 6.1h of sunshine, are months with the least sunshine in Cozumel.

How long on average sun shines in September in Cozumel?

In September, the average sunshine is 6.1h.

What is the UV index reading in September in Cozumel?

In Cozumel, Mexico, the average daily maximum UV index in September is 11. A UV Index value of 11, and more, symbolizes an extreme health vulnerability from unprotected exposure to the UV radiation.

Average temperature in September
Cozumel, Mexico

Average temperature in September - Cozumel, Mexico
  • Average high temperature in September: 31.9°C

The warmest month (with the highest average high temperature) is August (33°C).
Months with the lowest average high temperature are January and December (28.6°C).

  • Average low temperature in September: 23.6°C

The month with the highest average low temperature is June (23.8°C).
The coldest months (with the lowest average low temperature) are January and February (19.4°C).

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Average humidity in September
Cozumel, Mexico

Average humidity in September - Cozumel, Mexico
  • Average humidity in September: 87%

The month with the highest relative humidity is September (87%).
Months with the lowest relative humidity are March and April (79%).

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Average rainfall in September
Cozumel, Mexico

Average rainfall in September - Cozumel, Mexico
  • Average rainfall in September: 240.2mm

The wettest month (with the highest rainfall) is October (242.5mm).
The driest month (with the least rainfall) is March (32.2mm).

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Average rainfall days in September
Cozumel, Mexico

Average rainfall days in September - Cozumel, Mexico
  • Average rainfall days in September: 15.4 days

The month with the highest number of rainy days is October (15.7 days).
The month with the least rainy days is April (3.7 days).

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Average sea temperature in September
Cozumel, Mexico

Average sea temperature in September - Cozumel, Mexico
  • Average sea temperature in September: 29°C

The best months for swimming (with the highest average sea temperature) are July, August, September and October (29°C).
The coldest months (with the lowest average sea temperature) are February and March (26°C).

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Average daylight in September /
Average sunshine in September
Cozumel, Mexico

Average daylight in September / Average sunshine in September - Cozumel, Mexico
  • Average daylight in September: 12.2h

The month with the longest days is June (Average daylight: 13.4h).
The month with the shortest days is December (Average daylight: 10.9h).

  • Average sunshine in September: 6.1h

The month with the most sunshine is April (Average sunshine: 8.6h).
Months with the least sunshine are September and November (Average sunshine: 6.1).

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Average UV index in September
Cozumel, Mexico

Average UV index in September - Cozumel, Mexico
  • Average UV index in September: 11

Months with the highest UV index are April, May, June, July and August (UV index 12).
Months with the lowest UV index are January and December (UV index 7).

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