September weather forecast and climate
Port Isabel, TX

Weather in September

The first month of the autumn, September, is still a hot month in Port Isabel, Texas, with average temperature fluctuating between 86.2°F (30.1°C) and 80.4°F (26.9°C).

Temperature

In September, the average high-temperature is relatively the same as in August - a still hot 86.2°F (30.1°C). In September, the average low-temperature is 80.4°F (26.9°C).

Heat index

The average heat index is calculated to be a torrid 97.3°F (36.3°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'apparent temperature', 'real feel', or 'feels like', combines air temperature and relative humidity to represent a human perceived temperature equivalent. This effect is individual, with diverse people perceiving weather differently for numerous reasons (metabolic differences, clothing, differences in body mass, height, and shape), and activity. Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain 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. Under high air temperature and humidity (high heat index) conditions, perspiration is limited, and the perception of heat is increased. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 99.5°F (37.5°C) to 100.9°F (38.3°C), thermal conditions are potentially life-threatening.

Humidity

The average relative humidity in September is 74%.

Rainfall

September is the month with the most rainfall in Port Isabel. Rain falls for 19.8 days and accumulates 4.13" (105mm) of precipitation.

Ocean temperature

In September, the average ocean temperature is 84.6°F (29.2°C).
Note: For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

Daylight

In September, the average length of the day in Port Isabel is 12.3h.

Sunshine

The average sunshine in September is 9h.

UV index

April through September, with an average maximum UV index of 7, are months with the highest UV index in Port Isabel. A UV Index value of 6 to 7 symbolizes a high health hazard from unsafe exposure to the UV radiation for the ordinary person.
Note: The average daily UV index of 7 transform into the following instructions:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.
[Resources]

FAQ

What is the temperature in September in Port Isabel?

In September, the average high-temperature is 86.2°F (30.1°C), and the average low-temperature is 80.4°F (26.9°C). The average heat index (a.k.a. 'feels like', 'real feel'), which factors the actual air temperature with the relative humidity, in September is calculated to be 97.3°F (36.3°C).

What is the average humidity in September in Port Isabel?

In September, the average relative humidity in Port Isabel is 74%.

What is the rainiest month in Port Isabel?

September is the month with the most rainfall in Port Isabel. Rain falls for 19.8 days and accumulates 4.13" (105mm) of precipitation.

How much does it rain in Port Isabel in September?

In September, in Port Isabel, the rain falls for 19.8 days. Throughout September, 4.13" (105mm) of precipitation is accumulated.

How warm is the water in September in Port Isabel?

In Port Isabel, in September, the average water temperature is 84.6°F (29.2°C). Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

What is the average length of the day in September in Port Isabel?

In Port Isabel, Texas, the average length of the day in September is 12.3h.

How long on average sun shines in September in Port Isabel?

In September, the average sunshine is 9h.

What is the month with the highest UV index in Port Isabel?

April through September, with an average maximum UV index of 7, are months with the highest UV index in Port Isabel.

How high is the UV index in September in Port Isabel?

The average daily maximum UV index in September in Port Isabel, Texas, is 7. A UV Index estimate of 6 to 7 represents a high health risk from the exposure to the Sun's UV rays.

Average temperature in September
Port Isabel, TX

Average temperature in September - Port Isabel, TX
  • Average high temperature in September: 86.2°F

The warmest month (with the highest average high temperature) is August (88°F).
The month with the lowest average high temperature is January (67.1°F).

  • Average low temperature in September: 80.4°F

The month with the highest average low temperature is August (82°F).
The coldest month (with the lowest average low temperature) is January (59.5°F).

[Resources]

Average pressure in September
Port Isabel, TX

Average pressure in September - Port Isabel, TX
  • Average pressure in September: 29.91"

The month with the highest atmospheric pressure is January (30.11").
Months with the lowest atmospheric pressure are May and June (29.88").

[Resources]

Average wind speed in September
Port Isabel, TX

Average wind speed in September - Port Isabel, TX
  • Average wind speed in September: 10.9mph

The windiest month (with the highest average wind speed) is April (14.2mph).
The calmest month (with the lowest average wind speed) is September (10.9mph).

[Resources]

Average humidity in September
Port Isabel, TX

Average humidity in September - Port Isabel, TX
  • Average humidity in September: 74%

The month with the highest relative humidity is May (80%).
The month with the lowest relative humidity is October (72%).

[Resources]

Average rainfall in September
Port Isabel, TX

Average rainfall in September - Port Isabel, TX
  • Average rainfall in September: 4.13"

The wettest month (with the highest rainfall) is September (4.13").
The driest month (with the least rainfall) is April (0.51").

[Resources]

Average rainfall days in September
Port Isabel, TX

Average rainfall days in September - Port Isabel, TX
  • Average rainfall days in September: 19.8 days

The month with the highest number of rainy days is September (19.8 days).
The month with the least rainy days is March (8.2 days).

[Resources]

Average sea temperature in September
Port Isabel, TX

Average sea temperature in September - Port Isabel, TX
  • Average sea temperature in September: 84.6°F

The best month for swimming (with the highest average sea temperature) is August (85.1°F).
The coldest month (with the lowest average sea temperature) is February (66.7°F).

[Resources]

Average daylight in September /
Average sunshine in September
Port Isabel, TX

Average daylight in September / Average sunshine in September - Port Isabel, TX
  • Average daylight in September: 12.3h

The month with the longest days is June (Average daylight: 13.8h).
The month with the shortest days is December (Average daylight: 10.5h).

  • Average sunshine in September: 9h

The month with the most sunshine is July (Average sunshine: 11.3h).
The month with the least sunshine is December (Average sunshine: 4.8h).

[Resources]

Average sunshine days in September
Port Isabel, TX

Average sunshine days in September - Port Isabel, TX
  • Average sunshine days in September: 7.2 days

The month with the most sunshine days is March (20.7 days).
The month with the least sunshine days is September (7.2 days).

[Resources]

Average UV index in September
Port Isabel, TX

Average UV index in September - Port Isabel, TX
  • Average UV index in September: 7

Months with the highest UV index are April, May, June, July, August and September (UV index 7).
Months with the lowest UV index are January, February and December (UV index 5).

[Resources]

Average cloud cover in September
Port Isabel, TX

Average cloud cover in September - Port Isabel, TX
  • Average cloud cover in September: 29

The month with the most cloud cover is December (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 20).

[Resources]

Average visibility in September
Port Isabel, TX

Average visibility in September - Port Isabel, TX
  • Average visibility in September: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location