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

As San Marcos welcomes September, the average high-temperature records at a still tropical 30.5°C (86.9°F), marking an insignificant deviation from the prior month. San Marcos in September experiences a low-temperature average of 20.9°C (69.6°F).

Heat index

Throughout September, the heat index is computed to be a scorching 40°C (104°F). Exercise extra preventive actions, heat cramps and heat exhaustion are plausible. Continuous activity could result in heatstroke.
It is worth noting that heat index values are gauged for conditions in the shade and light breezes. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is found by incorporating humidity levels into the air temperature measurement. The influence of weather can be personal, changing with an individual's body mass, height, and level of physical exertion. Take note that direct exposure to the sun can increase the felt temperature, possibly adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are extremely vital to babies and toddlers. Youngsters generally face more threats than adults given their lesser ability to sweat. Coupled with their larger skin surface relative to their small bodies and higher heat production due to their activities, they are more endangered.
The body's natural response to excessive warmth is perspiration, as it allows for cooling through sweat evaporation. With an abundance of moisture present in the air, the process of evaporation becomes less effective, and the body fails to cool down as it should, leading to the sensation of overheating. The body is at risk of dehydration and related complications when it fails to shed excessive heat.

Humidity

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

Rainfall

In San Marcos, El Salvador, during September, the rain falls for 26.5 days and regularly aggregates up to 150mm (5.91") of precipitation. Throughout the year, in San Marcos, there are 196.7 rainfall days, and 1216mm (47.87") of precipitation is accumulated.

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 of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: In September, a daily maximum UV index of 6 leads to the following instructions:
Sustain precautions and conform to sun safety norms. Preventing sunburn is necessary. Be aware that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. and try to reduce direct sun exposure during this period as much as possible. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses.