September weather forecast
Houston, TX

A beautiful park in Root square overlooking the central business district of Houston, Texas, USA
A beautiful park in Root square overlooking the central business district of Houston, Texas, USA

Weather in September

The first month of the autumn, September, is still a tropical month in Houston, Texas, with an average temperature fluctuating between 72.7°F (22.6°C) and 88.3°F (31.3°C).

Temperature

In Houston, the average high-temperature in September marginally drops from 94.3°F (34.6°C) in August to a still hot 88.3°F (31.3°C). The average low-temperature, in Houston, is 72.7°F (22.6°C).

Heat index

The average heat index in September is evaluated at a torrid 103.5°F (39.7°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Note that heat index values are valued for light wind and location in the shade. 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', 'real feel', 'feels like', or 'felt air temperature', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (metabolic differences, wind, clothing). Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
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 exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

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

Rainfall

The month with the most rainfall is September, when the rain falls for 19.5 days and typically aggregates up to 4.49" (114mm) of precipitation.

Snowfall

In Houston, snow does not fall in February through November.

Daylight

In September, the average length of the day is 12h and 20min.
On the first day of the month, sunrise is at 6:58 am and sunset at 7:43 pm. On the last day of September, sunrise is at 7:14 am and sunset at 7:08 pm CDT.

Sunshine

In Houston, Texas, the average sunshine in September is 8.6h.

UV index

The average daily maximum UV index in September in Houston is 6. A UV Index value of 6 to 7 symbolizes a high health vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: The average daily UV index of 6 in September 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.
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FAQ

What is the temperature in September in Houston?

In Houston, Texas, in September, the average high-temperature is 88.3°F (31.3°C), and the average low-temperature is 72.7°F (22.6°C). The average heat index (a.k.a. 'feels like', 'felt air temperature'), which represents the influence of relative humidity on air temperature, in September is evaluated at 103.5°F (39.7°C).

What is the average humidity in September in Houston?

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

What is the wettest month in Houston?

The month with the most rainfall in Houston, Texas, is September, when the rain falls for 19.5 days and typically aggregates up to 4.49" (114mm) of precipitation.

How much does it rain in Houston in September?

In Houston, Texas, in September, during 19.5 rainfall days, 4.49" (114mm) of precipitation is typically accumulated.

When it does not snow in Houston?

In Houston, snow does not fall in February through November.

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

In September, the average day length in Houston, Texas, is 12h and 20min.

When is the sunrise / sunset in September in Houston?

In September, on the first day of the month, sunrise is at 6:58 am and sunset at 7:43 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 7:08 pm CDT.

How long on average sun shines in September in Houston?

In September, the average sunshine duration in Houston is 8.6h.

How high is the UV index in September in Houston?

In September, the average daily maximum UV index in Houston, Texas, is 6. A UV Index reading of 6 to 7 represents a high health risk from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Houston, TX

Average temperature in September - Houston, TX
  • Average high temperature in September: 88.3°F

The warmest month (with the highest average high temperature) is August (94.3°F).
The month with the lowest average high temperature is January (61.3°F).

  • Average low temperature in September: 72.7°F

The month with the highest average low temperature is August (77.5°F).
The coldest month (with the lowest average low temperature) is January (46°F).

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Average pressure in September
Houston, TX

Average pressure in September - Houston, TX
  • Average pressure in September: 29.96"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in September
Houston, TX

Average wind speed in September - Houston, TX
  • Average wind speed in September: 5.9mph

The windiest month (with the highest average wind speed) is April (8.6mph).
The calmest month (with the lowest average wind speed) is September (5.9mph).

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Average humidity in September
Houston, TX

Average humidity in September - Houston, TX
  • Average humidity in September: 74%

The month with the highest relative humidity is February (78%).
The months with the lowest relative humidity are August and October (70%).

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Average rainfall in September
Houston, TX

Average rainfall in September - Houston, TX
  • Average rainfall in September: 4.49"

The wettest month (with the highest rainfall) is September (4.49").
The driest month (with the least rainfall) is February (1.77").

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Average rainfall days in September
Houston, TX

Average rainfall days in September - Houston, TX
  • Average rainfall days in September: 19.5 days

The month with the highest number of rainy days is September (19.5 days).
The month with the least rainy days is January (11.8 days).

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Average snowfall in September
Houston, TX

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

The month with the highest snowfall is December (0.08").
The months with the least snowfall are February, March, April, May, June, July, August, September, October and November (0").

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Average snowfall days in September
Houston, TX

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

The months with the highest number of snowfall days are January and December (0.1 days).
The months with the least snowfall days are February, March, April, May, June, July, August, September, October and November (0 days).

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Average daylight in September /
Average sunshine in September
Houston, TX

Average daylight in September / Average sunshine in September - Houston, TX
  • Average daylight in September: 12h and 20min

The month with the longest days is June (Average daylight: 14h and 2min).
The month with the shortest days is December (Average daylight: 10h and 16min).

  • Average sunshine in September: 8h and 36min

The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is December (Average sunshine: 4h and 48min).

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Average sunshine days in September
Houston, TX

Average sunshine days in September - Houston, TX
  • Average sunshine days in September: 7.9 days

The month with the most sunshine days is January (16.3 days).
The month with the least sunshine days is September (7.9 days).

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Average UV index in September
Houston, TX

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

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

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Average cloud cover in September
Houston, TX

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

The month with the most cloud cover is February (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 27).

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Average visibility in September
Houston, TX

Average visibility in September - Houston, TX
  • Average visibility in September: 6mi

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

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