September weather forecast and climate
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
The first month of the autumn, September, is still a hot month in Houston, Texas, with temperature in the range of an average high of 88.3°F (31.3°C) and an average low of 72.7°F (22.6°C).

Temperature

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

Heat index

The average heat index 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 'felt air temperature', 'real feel', 'feels like', or 'apparent 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). 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. 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.
The human body normally cools itself by perspiration, as evaporated sweat carries heat away from the body. 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 surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

In September, the average relative humidity is 74%.

Rainfall

September is the month with the most rainfall. Rain falls for 19.5 days and accumulates 4.49" (114mm) of precipitation.

Snowfall

February through November are months without snowfall in Houston, Texas.

Daylight

The average length of the day in Houston is 12.3h.

Sunshine

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

UV index

The average daily maximum UV index in Houston is 6. A UV Index value of 6 to 7 symbolizes a high health vulnerability from the exposure to the Sun's UV rays for ordinary individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. 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.

What is the temperature in September in Houston?

The average high-temperature, in September, in Houston, is 88.3°F (31.3°C), while the average low-temperature is 72.7°F (22.6°C). The average heat index (a.k.a. 'apparent temperature', 'real feel'), that combines both air temperature and relative humidity, in September is appraised 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%.

How many days does it rain in September in Houston?

In Houston, in September, it is raining for 19.5 days, with typically 4.49" (114mm) of accumulated precipitation.

What is the rainiest 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.

When it does not snow in Houston?

In Houston snow does not fall in February through November.

How many hours of daylight does Houston have in September?

The average length of the day in September in Houston, Texas, is 12.3h.

How many hours of sunshine does Houston have in September?

The average sunshine in September is 8.6h.

What is the UV index intensity in September in Houston?

In September, the average daily maximum UV index is 6. A UV Index reading of 6 to 7 represents a high health vulnerability from unprotected exposure to the UV radiation.
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).

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

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

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).

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

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

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").

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).

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

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

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

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

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

The month with the longest days is June (Average daylight: 14h).
The month with the shortest days is December (Average daylight: 10.3h).

  • Average sunshine in September: 8.6h

The month with the most sunshine is August (Average sunshine: 10.5h).
The month with the least sunshine is December (Average sunshine: 4.8h).

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).

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

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).

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).

Average visibility in September - Houston, 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).