September weather forecast
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 an average temperature varying between 23.6°C (74.5°F) and 31.9°C (89.4°F).

Temperature

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

Heat index

In September, the average heat index is appraised at a burning hot 47°C (116.6°F). Beware: Heat cramps and heat exhaustion are very likely. Heatstroke is imminent with prolonged activity.
Note that heat index values are valued for light wind and location in the shade. 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 'real feel', 'felt air temperature', 'apparent temperature', or 'feels like', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (wind, clothing, 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. 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.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by 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

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

Rainfall

In Cozumel, during 15.4 rainfall days, 240mm (9.45") of precipitation is typically accumulated. Throughout the year, there are 119.9 rainfall days, and 1490mm (58.66") of precipitation is accumulated.

Sea temperature

July through October, with an average sea temperature of 29°C (84.2°F), are months with the warmest seawater.
Note: For swimming, diving, and other water activities, temperatures between 25°C (77°F) and 29°C (84.2°F) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

Daylight

The average length of the day in September is 12h and 15min.
On the first day of September in Cozumel, sunrise is at 6:31 am and sunset at 7:03 pm. On the last day of the month, sunrise is at 6:38 am and sunset at 6:36 pm EST.

Sunshine

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

UV index

In September, the average daily maximum UV index in Cozumel is 11. A UV Index estimate of 11, and higher, represents an extreme threat to health from unsafe exposure to UV radiation for average individuals.
Note: The average daily UV index of 11 in September transform into the following instructions:
Practice all essential precautions. Protection against sun damage is crucial. 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. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. A broad-spectrum sunscreen of SPF 30+ should be liberally applied and re-applied every two hours, and immediately after an outdoor workout or a swim. 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. 'real feel', 'felt air temperature'), which combines air temperature and relative humidity, in September is appraised at 47°C (116.6°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, in September, it is raining for 15.4 days, with typically 240mm (9.45") of accumulated 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.

How warm is the water in September in Cozumel?

In Cozumel, Mexico, the average seawater temperature in September 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?

In Cozumel, the average day length in September is 12h and 15min.

When is the sunrise / sunset in September in Cozumel?

In September, on the first day of the month, sunrise is at 6:31 am and sunset at 7:03 pm. On the last day of the month, in Cozumel, Mexico, sunrise is at 6:38 am and sunset at 6:36 pm EST.

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, Mexico.

How many hours of sunshine does Cozumel have in September?

In September, the average sunshine duration is 6.1h.

How high is the UV index in September in Cozumel?

In September, the average daily maximum UV index in Cozumel is 11. A UV Index estimate of 11, and higher, represents an extreme health vulnerability from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average sunshine
Average UV index

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).
The 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%).
The 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: 12h and 15min

The month with the longest days is June (Average daylight: 13h and 21min).
The month with the shortest days is December (Average daylight: 10h and 55min).

  • Average sunshine in September: 6h and 6min

The month with the most sunshine is April (Average sunshine: 8h and 36min).
The months with the least sunshine are September and November (Average sunshine: 6h and 6min).

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Average UV index in September
Cozumel, Mexico

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

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

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