September weather forecast
San Marcos, El Salvador

September marks a peak in cloud cover with 41%, somewhat reducing the sunlight hours during the day. Meanwhile, the month holds on to the wet season pattern, with 150mm (5.91") of rainfall across approximately 26 days. Equal energy balancing through wind is less operational as wind speed drops to an average value of 4.5 KPH. Despite the month-long wet conditions, September offers warm weather with an average UV index of 6 that remains consistent. It's noteworthy that this month paves the way for changes in weather, as the wet season is slowly winding down.

Temperature

San Marcos's weather in September displays an average high-temperature of a still hot 30.5°C (86.9°F), showing minor disparity from August's 31.6°C (88.9°F). During September, the average low-temperature is an agreeable 20.9°C (69.6°F).

Heat index

During September, the heat index is appraised at a blisteringly hot 40°C (104°F). More safety actions are required, heat exhaustion and heat cramps are probable. Long-term activity may precipitate heatstroke.
One should consider that heat index numbers are for shaded settings and light wind. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'feels like', gives a temperature feeling by integrating air temperature and humidity. The influence of weather is personal, differing among a variety of individuals based on differences in body mass, stature, and the level of physical activity. When in direct sunlight, one should be cautious as it can raise the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for children. Young ones often underestimate the need for rest and rehydration. Thirst appears late in dehydration - hence, it is important to keep hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

September and October, with an average relative humidity of 82%, are the most humid months in San Marcos.

Rainfall

In San Marcos, in September, it is raining for 26.5 days, with typically 150mm (5.91") of accumulated precipitation. In San Marcos, during the entire year, the rain falls for 196.7 days and collects up to 1216mm (47.87") of precipitation.

Daylight

In San Marcos, the average length of the day in September is 12h and 12min.
On the first day of the month, sunrise is at 05:45 and sunset at 18:07. On the last day of September, in San Marcos, sunrise is at 05:46 and sunset at 17:46 CST.

Sunshine

The average sunshine in September is 9h.

UV index

May through December, with an average maximum UV index of 6, are months with the lowest UV index. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for ordinary individuals.
Note: A daily high UV index of 6 in September leads to these guidelines:
Elude overexposure. Fair-skinned people could get burnt in less than 20 minutes. UV radiation from the sun is at its strongest between 10 a.m. and 4 p.m. Try to limit direct exposure during these hours. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses.