September is one of the warmer months of the year in Katy, with average highs near 32.3°C and lows around 21.3°C (mean 26.8°C). It is about average for rainfall, averaging 107 mm of rainfall and 73% relative humidity across the period.
September is one of the warmer months of the year in Katy. Across 45 years of records, the warmest September in Katy was 2023 — when the month averaged 30.9°C — while the coldest was 1983 at 24°C. Typical September days reach 32.3°C with nights near 21.3°C. The long-term trend is warming, about 0.5°C per decade.
September is about average for rainfall in Katy, averaging 107 mm of rainfall. The wettest September on record was 1998 with 281 mm, while the driest was 2025 at 32 mm.
Relative humidity in Katy during September averages 73%. The most humid Septembers were 1986 and 2018 at 84%, and the least humid was 2011 at 55%.
September receives about 5.1 kWh/m²/day of solar energy in Katy. The sunniest Septembers were 1999 and 2011 at 5.8 kWh/m²/day, and the cloudiest was 2018 at 3.7.
Average wind speed in Katy during September is 1.5 m/s. The windiest Septembers were 1985 and 2020 at 2 m/s, while the calmest were 2007, 2016 and 2022, among others at 1.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 26.0°C | 26.5°C | 26.3°C | 27.3°C | 28.4°C | +2.4°C |
| Avg High | 31.5°C | 32.0°C | 31.6°C | 32.6°C | 34.7°C | +3.2°C |
| Avg Low | 20.5°C | 21.0°C | 21.0°C | 22.0°C | 22.1°C | +1.6°C |
| Avg Rain | 100 mm | 118 mm | 115 mm | 115 mm | 74 mm | -26 mm |
September temperatures in Katy have risen by about 3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 7.4°C (1983) to a record high of 44.8°C (2000).
Rainfall in September is about average for rainfall, averaging 107 mm, with a wettest year of 281 mm.
One of the best times to visit Katy
September is one of the best times to visit Katy. Expect days averaging 32.3°C and nights around 21.3°C (mean 26.8°C) — warmer than Katy's yearly average — with higher rainfall (107 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 35.7°C | 28.8°C | 22.0°C | 38.2°C | 16.1°C | 32 mm | 63% | 1.3 m/s | 5.7 |
| 2024 | 35.2°C | 28.7°C | 22.2°C | 38.9°C | 16.5°C | 47 mm | 69% | 1.6 m/s | 5.1 |
| 2023 🔥 | 37.6°C | 30.9°C | 24.3°C | 43.4°C | 19.9°C | 60 mm | 61% | 1.4 m/s | 5.4 |
| 2022 | 34.2°C | 27.7°C | 21.2°C | 37.9°C | 13.0°C | 36 mm | 68% | 1.2 m/s | 5.7 |
| 2021 | 33.3°C | 27.2°C | 21.1°C | 37.4°C | 13.1°C | 116 mm | 71% | 1.5 m/s | 5.1 |
| 2020 | 31.9°C | 26.8°C | 21.6°C | 36.5°C | 11.2°C | 153 mm | 74% | 2 m/s | 4.6 |
| 2019 | 35.1°C | 29.4°C | 23.8°C | 40.3°C | 21.5°C | 180 mm | 71% | 1.8 m/s | 5.3 |
| 2018 | 30.9°C | 26.9°C | 22.9°C | 35.2°C | 18.8°C | 194 mm | 84% | 1.4 m/s | 3.7 |
| 2017 | 30.2°C | 25.1°C | 20.1°C | 32.4°C | 14.3°C | 46 mm | 80% | 1.3 m/s | 5.6 |
| 2016 | 31.7°C | 27.1°C | 22.5°C | 34.6°C | 13.8°C | 76 mm | 81% | 1.2 m/s | 5.2 |
| 2015 | 32.2°C | 26.8°C | 21.4°C | 35.4°C | 14.2°C | 100 mm | 76% | 1.3 m/s | 5.2 |
| 2014 | 31.2°C | 26.7°C | 22.1°C | 36.3°C | 15.9°C | 145 mm | 80% | 1.4 m/s | 4.7 |
| 2013 | 33.4°C | 28.0°C | 22.6°C | 37.7°C | 16.0°C | 150 mm | 73% | 1.6 m/s | 5 |
| 2012 | 33.2°C | 27.0°C | 20.9°C | 38.1°C | 15.3°C | 93 mm | 71% | 1.5 m/s | 5.3 |
| 2011 | 36.2°C | 28.7°C | 21.2°C | 40.8°C | 15.1°C | 43 mm | 55% | 1.8 m/s | 5.8 |
| 2010 | 32.3°C | 27.3°C | 22.2°C | 34.9°C | 12.5°C | 124 mm | 76% | 1.5 m/s | 4.9 |
| 2009 | 31.3°C | 26.3°C | 21.3°C | 35.5°C | 16.5°C | 105 mm | 77% | 1.4 m/s | 4.1 |
| 2008 | 30.4°C | 24.9°C | 19.4°C | 36.3°C | 14.2°C | 181 mm | 75% | 1.8 m/s | 5.5 |
| 2007 | 30.6°C | 26.2°C | 21.7°C | 32.4°C | 17.4°C | 81 mm | 83% | 1.2 m/s | 5 |
| 2006 | 31.9°C | 26.1°C | 20.4°C | 35.1°C | 13.0°C | 84 mm | 73% | 1.6 m/s | 5.2 |
| 2005 | 35.5°C | 29.4°C | 23.4°C | 39.2°C | 20.0°C | 68 mm | 69% | 1.7 m/s | 5.2 |
| 2004 | 33.7°C | 27.8°C | 21.8°C | 38.1°C | 18.0°C | 36 mm | 68% | 1.4 m/s | 5.3 |
| 2003 | 28.8°C | 24.3°C | 19.8°C | 31.5°C | 12.1°C | 178 mm | 82% | 1.3 m/s | 4.9 |
| 2002 | 30.3°C | 25.6°C | 21.0°C | 34.4°C | 15.9°C | 177 mm | 80% | 1.9 m/s | 4.7 |
| 2001 | 29.2°C | 24.7°C | 20.2°C | 33.2°C | 10.5°C | 145 mm | 82% | 1.4 m/s | 5.4 |
| 2000 | 34.0°C | 27.4°C | 20.8°C | 44.8°C | 9.8°C | 92 mm | 62% | 1.8 m/s | 5.7 |
| 1999 | 33.9°C | 27.1°C | 20.3°C | 38.8°C | 12.4°C | 67 mm | 60% | 1.6 m/s | 5.8 |
| 1998 🌧️ | 32.0°C | 27.7°C | 23.4°C | 38.1°C | 21.5°C | 281 mm | 81% | 1.7 m/s | 4.9 |
| 1997 | 33.4°C | 27.5°C | 21.6°C | 37.0°C | 15.6°C | 148 mm | 71% | 1.5 m/s | 5.3 |
| 1996 | 29.7°C | 25.1°C | 20.5°C | 32.2°C | 9.7°C | 194 mm | 80% | 1.3 m/s | 5.1 |
| 1995 | 33.2°C | 27.2°C | 21.3°C | 38.2°C | 10.9°C | 67 mm | 70% | 1.3 m/s | 5.5 |
| 1994 | 30.9°C | 25.2°C | 19.5°C | 34.6°C | 9.7°C | 77 mm | 73% | 1.3 m/s | 5.5 |
| 1993 | 34.2°C | 27.4°C | 20.5°C | 37.7°C | 12.0°C | 47 mm | 65% | 1.7 m/s | 5.4 |
| 1992 | 32.0°C | 26.7°C | 21.4°C | 34.5°C | 11.1°C | 66 mm | 74% | 1.7 m/s | 4.9 |
| 1991 | 28.8°C | 24.3°C | 19.8°C | 31.8°C | 10.9°C | 134 mm | 83% | 1.4 m/s | 4.8 |
| 1990 | 31.8°C | 26.7°C | 21.6°C | 37.1°C | 11.4°C | 100 mm | 75% | 1.2 m/s | 5 |
| 1989 | 31.5°C | 25.1°C | 18.7°C | 37.4°C | 9.8°C | 49 mm | 69% | 1.5 m/s | 5.5 |
| 1988 | 33.6°C | 27.3°C | 21.0°C | 36.5°C | 15.5°C | 74 mm | 69% | 1.9 m/s | 5 |
| 1987 | 31.8°C | 26.1°C | 20.4°C | 35.9°C | 13.9°C | 99 mm | 71% | 1.5 m/s | 5.3 |
| 1986 | 30.7°C | 26.9°C | 23.1°C | 32.5°C | 21.1°C | 144 mm | 84% | 1.6 m/s | 4.6 |
| 1985 | 32.1°C | 26.7°C | 21.3°C | 40.0°C | 10.2°C | 146 mm | 71% | 2 m/s | 5.2 |
| 1984 | 30.9°C | 25.4°C | 19.9°C | 35.2°C | 9.9°C | 87 mm | 72% | 1.9 m/s | 4.6 |
| 1983 ❄️ | 28.7°C | 24.0°C | 19.4°C | 32.6°C | 7.4°C | 201 mm | 83% | 1.6 m/s | — |
| 1982 | 34.2°C | 27.7°C | 21.1°C | 38.0°C | 12.3°C | 40 mm | 64% | 1.7 m/s | — |
| 1981 | 29.8°C | 24.7°C | 19.6°C | 32.1°C | 10.1°C | 62 mm | 78% | 1.3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 32.3°C with lows near 21.3°C (mean 26.8°C), based on 45 years of NASA POWER data.
September averages 107 mm of rainfall in Katy, about average for rainfall. The wettest on record was 281 mm in 1998.
The hottest September reached 44.8°C in 2000. The coldest dipped to 7.4°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 3°C. Daytime highs moved from 31.1°C to 35.2°C and overnight lows from 20.3°C to 22.2°C over the same span.
September is one of the warmer months of the year in Katy and about average for rainfall, so plan for around 32.3°C daytime highs and 21.3°C at night.
Not quite — September is the 9th coolest month in Katy, averaging 26.8°C.
For September in Katy, pack light, breathable clothing and sun protection, with typical highs of 32.3°C and lows of 21.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 73% — moderately humid.
Average wind speed in September is 1.5 m/s. The windiest September on record averaged 2 m/s (1985).
The wettest September on record was 1998 with 281 mm. On average, September sees 107 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Katy behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
