September weather forecast
Cozumel, Mexico

In September, the weather in Cozumel begins a gradual transition towards the cooler months. A slight dip in daylight hours is compensated by increased sunshine, providing abundant hours for outdoor pursuits. The UV index drops to 11, but sun protection remains a must. Torrential showers grace the city in September, where the monthly rainfall achieves a maximum of 240mm (9.45").

Temperature

Shifting into September, Cozumel records an average high-temperature of a still hot 31.9°C (89.4°F), presenting minor fluctuations compared to the previous month. Cozumel's temperature in September lowers to a consistent average of 23.6°C (74.5°F) during the nights.

Heat index

In September, the heat index is calculated to be a blazing hot 47°C (116.6°F). Beware: Heat exhaustion along with heat cramps are on the cards. Heatstroke could result from sustained physical activity.
One should be cognizant that the heat index values are tailored for shaded spots and mild winds. An exposure to direct sunlight may lift the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is an estimation of the warmth sensation when considering humidity levels. The effect is experienced differently by individuals, hinging on unique characteristics such as body mass, stature, and level of activity. It is essential to realize that direct sunlight can escalate the perceived temperature, increasing the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical for babies and toddlers. Young ones generally face higher dangers than adults since they sweat less. Along with their large skin surface area compared totheir small bodies and increased heat production from their activities, the risks are heightened.
Evaporating sweat, thanks to perspiration, acts as a natural air conditioner for the human body. Under conditions of increased relative humidity, the evaporation rate lessens, causing the body to retain more heat than under less humid conditions. Temperature imbalances caused by excessive heat retention can trigger heat-related maladies.

Humidity

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

Rainfall

In Cozumel, in September, it is raining for 15.4 days, with typically 240mm (9.45") of accumulated precipitation. 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 in Cozumel.
Note: For any water activity, having surface water temperatures from 25°C (77°F) to 29°C (84.2°F) is considered outstanding and highly delightful for lengthened periods.

Daylight

In Cozumel, the average length of the day in September is 12h and 15min.
On the first day of the month, sunrise is at 6:31 am and sunset at 7:02 pm. On the last day of September, sunrise is at 6:38 am and sunset at 6:36 pm EST.

Sunshine

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

UV index

In September, the average daily maximum UV index in Cozumel is 11. A UV Index value of 11, and more, symbolizes an ultimate health vulnerability from exposure to the Sun's UV rays for the average person.
Note: In September, a daily UV index of 11 turns into the following recommendations:
Ensure every key safety measure. People with light skin might sustain burns in fewer than 5 minutes. Stay out of direct sunlight and seek shade between 10 a.m. and 4 p.m., when UV radiation is strongest, but remember that shade devices may not offer full sun protection. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses. Prompt application of a broad-spectrum sunscreen, SPF 30+, is necessary after a swim or an outdoor workout and it should be re-applied every two hours. Stay aware! UV radiation is magnified when reflecting off sand and water.