September weather forecast
Merida, Mexico

With the commencement of September, the weather takes another turn in Merida. The city receives the highest amount of rainfall, up to 70mm (2.76") on average, as compared to other months. Even though the rainfall is significant, temperatures remain quite high. The overall weather can be described as rainy and humid, making it ideal for indoor activities. Since outdoor activities may get hindered due to significant rainfall, flexible plans are advised.

Temperature

Merida's average high-temperature in September sits at a hot 33.6°C (92.5°F), showing little difference from the previous month. Throughout September, Merida experiences a low-temperature average of 23.3°C (73.9°F).

Heat index

During September, the heat index is estimated at a life-threatening hot 49°C (120.2°F). Careful: Heat exhaustion and heat cramps are anticipated. With ongoing exertion, heatstroke becomes a possibility.
Be advised, the heat index considers values for conditions in shade and with a light breeze. A rise in the heat index by 15 Fahrenheit (8 Celsius) degrees may result from direct sunlight exposure.
Note: The heat index, also known as 'feels like' or 'felt air temperature', shows a temperature sensation when both heat and moisture conditions are combined. An individual's perception of weather can be influenced by a variety of factors including metabolic differences, being pregnant, and their degree of physical exertion. One should be aware that direct sunshine can amplify the perceived temperature, raising the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are largely significant for babies and toddlers. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
The physiological way the human body responds to excessive heat is by inducing perspiration, using sweat evaporation as a cooling mechanism. During high air temperature and humidity (high heat index), the process of perspiration is hindered, intensifying the sensation of heat. As the body accumulates more heat than it can release, body temperature goes up, increasing the risk of heat-related health issues.

Humidity

September and October, with an average relative humidity of 78%, are the most humid months.

Rainfall

In Merida, in September, it is raining for 20.4 days, with typically 70mm (2.76") of accumulated precipitation. Throughout the year, there are 167.3 rainfall days, and 536mm (21.1") of precipitation is accumulated.

Daylight

In September, the average length of the day is 12h and 16min.
On the first day of September, sunrise is at 5:42 am and sunset at 6:13 pm. On the last day of the month, sunrise is at 5:49 am and sunset at 5:46 pm CST.

Sunshine

In September, the average sunshine is 9.4h.

UV index

February through October, with an average maximum UV index of 7, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high health risk from unprotected exposure to Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 7 translates into the following recommendations:
Enforce precautions and stick to sun safety measures. Preservation from skin and eye damage is essential. Try to minimize direct Sun exposure between 10 a.m. and 4 p.m., the peak period for UV radiation. Also note that objects like parasols or canopies might not provide complete sun protection. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.