September weather forecast
Brownsville, TX

In Brownsville, September brings a gradual respite from summer heat with temperatures starting their return journey towards annual mean values. Rainfall picks up pace, accumulating to 1.81" (46mm) - the highest in the year, making the weather a mix of wet and hot sensation. A significant decrease in wind speed and pressure corresponds to the transition to the fall season. The gradual reduction in daylight hours commences as days start shrinking. Though sunshine hours drop, they still provide an ample amount of light during the day.

Temperature

With the onset of September, a modest change to a still hot 89.4°F (31.9°C) from August's 93.2°F (34°C) is noted in high-temperature. An average low-temperature of 78.8°F (26°C) is common during the nights of September.

Heat index

For September, the heat index is evaluated at a blisteringly hot 104°F (40°C). Extra precautions are necessary, heat cramps and heat exhaustion are plausible outcomes. Extended activity could lead to heatstroke.
One should consider that heat index numbers are for shaded settings and light wind. Heat index values have the potential to be boosted by 15 Fahrenheit (8 Celsius) degrees due to direct sunlight.
Note: The heat index, also known as 'feels like' or 'felt air temperature', is a composite of temperature and humidity figures to convey how warm it feels. A person's impression of weather can be shaped by several aspects, among them metabolic variations, pregnancy, and levels of physical activity. Do note, being directly under sun rays can amplify the heat you feel, potentially raising the heat index by 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.
Perspiration is the body's default response to elevated temperatures, as it promotes the evaporation of sweat to achieve cooling. Augmented relative humidity impedes typical body cooling mechanisms by lowering the evaporation rate, resulting in decreased body cooling and an amplified perception of heat. Heat disorders may be on the horizon when body temperatures rise from inadequate heat management.

Humidity

In Brownsville, the average relative humidity in September is 70%.

Rainfall

September is the month with the most rainfall. Rain falls for 14.4 days and accumulates 1.81" (46mm) of precipitation.

Daylight

In Brownsville, the average length of the day in September is 12h and 17min.
On the first day of September, sunrise is at 7:10 am and sunset at 7:49 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 7:17 pm CDT.

Sunshine

The average sunshine in September is 8.9h.

UV index

In Brownsville, the average daily maximum UV index in September is 7. A UV Index value of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV rays for ordinary individuals.
Note: In September, a daily maximum UV index of 7 leads to the following instructions:
Persist with safeguards and heed sun safety doctrines. Keeping sunburn at bay is of prime importance. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.