Last updated: June 24, 2025
In September, the average temperature in Houston, United States hovers around 9°C (48°F). Expect a chilly minimum of -6°C (21°F) and a comfortable maximum of 20°C (69°F). With 106 mm (4.2 in) of precipitation spread across 18 days, you'll want to be prepared for rain. The air is often quite damp, featuring an average humidity of 96%.
In September in Houston, the average temperature is 9°C (48°F), with maximums that can reach 20°C (69°F) and minimums that can drop as low as -6°C (21°F). It's advisable to pack layers and be prepared for varying weather conditions if you plan to travel during this time.
In Houston in September, the precipitation amount is 106 mm (4.2 in), occurring over 18 days.
In Houston in September humidity is 96%. With an average temperature of 9°C (48°F), this humidity feels like a chilly blanket wrapping around you, making outdoor activities uncomfortable unless you're dressed in layers to combat both the cold and dampness.
In Houston in September, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Houston for better planning.
UV Risk Categories
Weather in Houston varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Houston, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -12°C (11°F) | 38 mm (1.5 inches) | 94% | low |
| February Weather | -9°C (16°F) | 49 mm (1.9 inches) | 93% | low |
| March Weather | -6°C (21°F) | 42 mm (1.7 inches) | 91% | moderate |
| April Weather | 2°C (36°F) | 43 mm (1.7 inches) | 85% | moderate |
| May Weather | 9°C (48°F) | 99 mm (3.9 inches) | 88% | high |
| June Weather | 13°C (55°F) | 98 mm (3.9 inches) | 95% | high |
| July Weather | 15°C (60°F) | 103 mm (4.0 inches) | 102% | high |
| August Weather | 13°C (56°F) | 152 mm (6.0 inches) | 100% | moderate |
| September Weather | 9°C (48°F) | 106 mm (4.2 inches) | 96% | moderate |
| October Weather | 2°C (37°F) | 109 mm (4.3 inches) | 91% | low |
| November Weather | -7°C (20°F) | 63 mm (2.5 inches) | 95% | low |
| December Weather | -8°C (18°F) | 76 mm (3.0 inches) | 96% | low |