September weather forecast and climate
Austin, TX

The beautiful Lady Bird Lake passing through the city skyscrapers of Austin city, Texas
The beautiful Lady Bird Lake passing through the city skyscrapers of Austin city, Texas
The first month of the autumn, September, is still a hot month in Austin, Texas, with average temperature varying between 88.2°F (31.2°C) and 70.9°F (21.6°C).

Temperature

In Austin, the average high-temperature slightly decreases, from a torrid 96.4°F (35.8°C) in August, to a hot 88.2°F (31.2°C). The average low-temperature, in September, is 70.9°F (21.6°C).

Heat index

In September, the average heat index is calculated to a sweltering 99.5°F (37.5°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 'apparent temperature', 'felt air temperature', 'real feel', or 'feels like', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (pregnancy, differences in body mass, height, and shape, clothing). Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, 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.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. With a lot of moisture in the air, the evaporation process is not as effective, and the body does not cool down as efficiently, creating a perception of overheating. 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 68%.

Rainfall

In Austin, in September, during 15.1 rainfall days, 2.52" (64mm) of precipitation is typically accumulated. Throughout the year, there are 142.7 rainfall days, and 21.5" (546mm) of precipitation is accumulated.

Snowfall

In Austin snow does not fall in March through December.

Daylight

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

Sunshine

The average sunshine in September is 8.4h.

UV index

The average daily maximum UV index in Austin is 6. A UV Index reading of 6 to 7 represents a high threat to health from the exposure to the Sun's UV rays for the ordinary person.
Note: The average daily UV index of 6 in September transform into the following instructions:
Take precautions against overexposure. Protection against sun damage is needed. 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. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in Austin?

In September, in Austin, Texas, the average high-temperature is 88.2°F (31.2°C), and the average low-temperature is 70.9°F (21.6°C). In September, the average heat index (a.k.a. 'feels like', 'felt air temperature'), that combines air temperature and relative humidity, is evaluated at 99.5°F (37.5°C).

What is the average humidity in September in Austin?

The average relative humidity in September in Austin, Texas, is 68%.

How many days does it rain in September in Austin?

In Austin, during September, the rain falls for 15.1 days and regularly aggregates up to 2.52" (64mm) of precipitation.

When it does not snow in Austin?

In Austin snow does not fall in March through December.

What is the average length of the day in September in Austin?

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

How long on average sun shines in September in Austin?

In Austin, the average sunshine in September is 8.4h.

What is the UV index reading in September in Austin?

In Austin, the average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health vulnerability from the exposure to the Sun's UV rays.
Average temperature in September - Austin, TX
  • Average high temperature in September: 88.2°F

The warmest month (with the highest average high temperature) is August (96.4°F).
The month with the lowest average high temperature is January (59.4°F).

  • Average low temperature in September: 70.9°F

The month with the highest average low temperature is August (75.4°F).
The coldest month (with the lowest average low temperature) is January (42.6°F).

Average pressure in September - Austin, TX
  • Average pressure in September: 29.96"

The month with the highest atmospheric pressure is January (30.15").
The month with the lowest atmospheric pressure is June (29.91").

Average wind speed in September - Austin, TX
  • Average wind speed in September: 6.2mph

The windiest month (with the highest average wind speed) is March (9.2mph).
The calmest month (with the lowest average wind speed) is September (6.2mph).

Average humidity in September - Austin, TX
  • Average humidity in September: 68%

The month with the highest relative humidity is May (75%).
The month with the lowest relative humidity is August (59%).

Average rainfall in September - Austin, TX
  • Average rainfall in September: 2.52"

The wettest month (with the highest rainfall) is May (3.78").
The driest month (with the least rainfall) is February (0.91").

Average rainfall days in September - Austin, TX
  • Average rainfall days in September: 15.1 days

The month with the highest number of rainy days is May (16.2 days).
The month with the least rainy days is January (8.2 days).

Average snowfall in September - Austin, TX
  • Average snowfall in September: 0"

The month with the highest snowfall is January (0.4").
Months with the least snowfall are March, April, May, June, July, August, September, October, November and December (0").

Average snowfall days in September - Austin, TX
  • Average snowfall days in September: 0 days

Months with the highest number of snowfall days are January and February (0.3 days).
Months with the least snowfall days are March, April, May, June, July, August, September, October and December (0 days).

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

The month with the longest days is June (Average daylight: 14.1h).
The month with the shortest days is December (Average daylight: 10.2h).

  • Average sunshine in September: 8.4h

Months with the most sunshine are July and August (Average sunshine: 10.3h).
The month with the least sunshine is December (Average sunshine: 5.3h).

Average sunshine days in September - Austin, TX
  • Average sunshine days in September: 12.5 days

The month with the most sunshine days is January (20.5 days).
The month with the least sunshine days is May (11.1 days).

Average UV index in September - Austin, TX
  • Average UV index in September: 6

Months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).

Average cloud cover in September - Austin, TX
  • Average cloud cover in September: 32

The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is August (Cloud cover 24).

Average visibility in September - Austin, 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).