September weather forecast
Cancún, Mexico

As Cancún transitions from the height of summer in August to more moderate conditions in September, there's a marginal reduction in temperatures. September is noted for the high precipitation levels often resulting in intermittent bouts of increased humidity. Despite the rainfall, temperatures remain on the higher side providing ample warmth to beach-goers. Cancún’s weather in September is marked by a high temperature of 30.3°C (86.5°F), a low oscillating towards 26.7°C (80.1°F), and significant rainfall measuring 91mm (3.58") distributed over approximately 21.5 days. Conclusively, despite the diminishing summer heat, the city maintains an inviting ambience marked by occasional periods of refreshing rain.

Temperature

With the onset of September, Cancún's average high-temperature clocks in at a still tropical 30.3°C (86.5°F), showing a minor fluctuation from the previous month. Cancún's September nights observe a minor shift from the daytime temperatures, resulting in an average dip to a moderately hot 26.7°C (80.1°F).

Heat index

During September, the heat index is appraised at a very hot 38°C (100.4°F). Adopt special protective actions against heat exhaustion and heat cramps. Long-duration activity risks heatstroke.
Keep in mind the heat index values are meant for areas in shade and with light wind. Exposure to direct sunshine can increase heat index values by up to 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 individual's impression of temperature can be shaped by additional aspects such as metabolic variations, physical activity, and clothing. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. Children often overlook the necessity for resting and fluid replenishment. Thirst is a late sign of dehydration - thus, it is critical to stay hydrated, especially during extended periods of physical activities.
The physiological way the human body responds to excessive heat is by inducing perspiration, using sweat evaporation as a cooling mechanism. An increase in relative humidity disrupts body cooling by slowing the evaporation rate, thereby reducing the rate at which the body cools and amplifying the sense of heat. When the body is unable to balance heat gain, its temperature elevates, which may induce thermal illnesses.

Humidity

In September, the average relative humidity in Cancún is 77%.

Rainfall

In September, the rain falls for 21.5 days. Throughout September, 91mm (3.58") of precipitation is accumulated. In Cancún, during the entire year, the rain falls for 224.7 days and collects up to 886mm (34.88") of precipitation.

Sea temperature

In Cancún, the average seawater temperature in September is 29.3°C (84.7°F).
Note: Water activities in surface temperatures between 25°C (77°F) and 29°C (84.2°F) are seen as exceptional and extremely agreeable for lengthened time spans.

Daylight

In Cancún, the average length of the day in September is 12h and 16min.
On the first day of September, 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 6:35 pm EST.

Sunshine

The average sunshine in September is 9.2h.

UV index

The months with the highest UV index in Cancún are March through October, with an average maximum UV index of 7. A UV Index value of 6 to 7 symbolizes a high health hazard from unsafe exposure to UV radiation for average individuals.
Note: In September, the maximum UV index of 7 suggests these recommendations:
Use protective steps and abide by sun safety guidelines. Safeguarding against skin and eye harm is necessary. The hours from 10 a.m. to 4 p.m. have the most intense UV radiation. As much as possible, limit direct sun exposure during this period. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Beware! Reflecting off water and sand, UV rays are much stronger.