September is one of the warmer months of the year in Killeen, with average highs near 32.7°C and lows around 20.5°C (mean 26.6°C). It is about average for rainfall, averaging 71 mm of rainfall and 63% relative humidity across the period.
September is one of the warmer months of the year in Killeen. Across 45 years of records, the warmest September in Killeen was 2019 — when the month averaged 30.5°C — while the coldest was 1991 at 23.8°C. Typical September days reach 32.7°C with nights near 20.5°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Killeen, averaging 71 mm of rainfall. The wettest September on record was 2010 with 193 mm, while the driest was 2008 at 15 mm.
Relative humidity in Killeen during September averages 63%. The most humid September was 2018 at 80%, and the least humid was 2011 at 39%.
September receives about 5.3 kWh/m²/day of solar energy in Killeen. The sunniest September was 2011 at 6.2 kWh/m²/day, and the cloudiest was 2009 at 4.2.
Average wind speed in Killeen during September is 2.4 m/s. The windiest September was 1984 at 3.4 m/s, while the calmest was 2022 at 1.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 26.1°C | 26.3°C | 26.1°C | 27.3°C | 27.6°C | +1.5°C |
| Avg High | 32.4°C | 32.3°C | 32.0°C | 33.2°C | 34.1°C | +1.7°C |
| Avg Low | 19.8°C | 20.2°C | 20.1°C | 21.4°C | 21.2°C | +1.4°C |
| Avg Rain | 64 mm | 74 mm | 66 mm | 84 mm | 63 mm | -1 mm |
September temperatures in Killeen have risen by about 2.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 6.8°C (1984) to a record high of 44.5°C (2000).
Rainfall in September is about average for rainfall, averaging 71 mm, with a wettest year of 193 mm.
One of the best times to visit Killeen
September is one of the best times to visit Killeen. Expect days averaging 32.7°C and nights around 20.5°C (mean 26.6°C) — warmer than Killeen's yearly average — with moderate rainfall (71 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 | 34.7°C | 27.8°C | 20.9°C | 38.7°C | 15.9°C | 30 mm | 56% | 1.9 m/s | 5.8 |
| 2024 | 34.6°C | 27.8°C | 21.1°C | 38.8°C | 14.3°C | 38 mm | 59% | 2.5 m/s | 5.4 |
| 2023 | 36.7°C | 30.2°C | 23.7°C | 44.0°C | 19.6°C | 60 mm | 56% | 2.3 m/s | 5.5 |
| 2022 | 34.5°C | 27.8°C | 21.1°C | 38.5°C | 15.0°C | 28 mm | 57% | 1.8 m/s | 5.9 |
| 2021 | 34.7°C | 27.9°C | 21.1°C | 39.2°C | 14.9°C | 49 mm | 55% | 2.2 m/s | 5.8 |
| 2020 | 29.1°C | 24.2°C | 19.3°C | 33.7°C | 10.7°C | 174 mm | 76% | 2.8 m/s | 4.4 |
| 2019 🔥 | 37.0°C | 30.5°C | 24.0°C | 39.7°C | 22.0°C | 18 mm | 58% | 2.7 m/s | 5.8 |
| 2018 | 30.2°C | 25.9°C | 21.7°C | 37.4°C | 15.5°C | 179 mm | 80% | 2 m/s | 4.4 |
| 2017 | 32.8°C | 26.3°C | 19.9°C | 36.3°C | 13.6°C | 44 mm | 66% | 2.5 m/s | 5.5 |
| 2016 | 31.6°C | 26.5°C | 21.4°C | 36.0°C | 12.2°C | 61 mm | 74% | 2 m/s | 5.4 |
| 2015 | 34.7°C | 28.4°C | 22.1°C | 39.1°C | 17.3°C | 21 mm | 58% | 2.2 m/s | 5.6 |
| 2014 | 31.9°C | 26.5°C | 21.0°C | 38.0°C | 14.4°C | 88 mm | 70% | 2.2 m/s | 4.9 |
| 2013 | 33.4°C | 27.5°C | 21.7°C | 38.7°C | 13.9°C | 116 mm | 63% | 2.1 m/s | 5.3 |
| 2012 | 32.8°C | 26.3°C | 19.8°C | 40.6°C | 14.8°C | 106 mm | 61% | 2.6 m/s | 5.4 |
| 2011 | 36.4°C | 28.7°C | 21.1°C | 41.5°C | 15.5°C | 18 mm | 39% | 2.7 m/s | 6.2 |
| 2010 🌧️ | 31.5°C | 26.2°C | 20.9°C | 37.4°C | 11.3°C | 193 mm | 73% | 2.5 m/s | 5.3 |
| 2009 | 29.5°C | 24.8°C | 20.1°C | 37.7°C | 14.3°C | 177 mm | 74% | 2.4 m/s | 4.2 |
| 2008 | 32.9°C | 26.1°C | 19.3°C | 37.5°C | 13.9°C | 15 mm | 58% | 2.5 m/s | 5.5 |
| 2007 | 30.2°C | 25.5°C | 20.7°C | 32.2°C | 18.2°C | 70 mm | 79% | 1.9 m/s | 5.2 |
| 2006 | 32.5°C | 26.0°C | 19.5°C | 38.1°C | 13.2°C | 61 mm | 61% | 2.6 m/s | 5.2 |
| 2005 | 35.5°C | 28.9°C | 22.4°C | 42.3°C | 18.7°C | 26 mm | 60% | 2.4 m/s | 5.5 |
| 2004 | 32.6°C | 26.3°C | 19.9°C | 36.1°C | 14.7°C | 24 mm | 63% | 2.1 m/s | 5.3 |
| 2003 | 30.9°C | 25.0°C | 19.1°C | 36.1°C | 13.0°C | 82 mm | 68% | 2.2 m/s | 5.1 |
| 2002 | 32.4°C | 26.3°C | 20.2°C | 37.7°C | 12.9°C | 73 mm | 64% | 2.6 m/s | 5.2 |
| 2001 | 29.7°C | 24.5°C | 19.3°C | 33.9°C | 10.5°C | 73 mm | 74% | 2.3 m/s | 5.5 |
| 2000 | 34.2°C | 27.2°C | 20.3°C | 44.5°C | 8.2°C | 53 mm | 52% | 2.6 m/s | 5.5 |
| 1999 | 34.7°C | 27.7°C | 20.6°C | 39.5°C | 10.1°C | 19 mm | 47% | 2.9 m/s | 5.8 |
| 1998 | 33.4°C | 28.1°C | 22.8°C | 40.8°C | 20.7°C | 114 mm | 70% | 2.4 m/s | 4.9 |
| 1997 | 35.1°C | 28.4°C | 21.6°C | 39.1°C | 15.0°C | 31 mm | 57% | 2.5 m/s | 5.5 |
| 1996 | 29.6°C | 24.4°C | 19.2°C | 33.1°C | 8.9°C | 119 mm | 74% | 2 m/s | 5.1 |
| 1995 | 32.6°C | 26.3°C | 20.1°C | 39.5°C | 8.0°C | 74 mm | 65% | 2.4 m/s | 5 |
| 1994 | 31.6°C | 25.0°C | 18.5°C | 36.7°C | 8.9°C | 55 mm | 63% | 2.5 m/s | 5.3 |
| 1993 | 33.0°C | 26.1°C | 19.3°C | 38.0°C | 11.3°C | 80 mm | 58% | 2.6 m/s | 5.5 |
| 1992 | 32.8°C | 26.5°C | 20.3°C | 36.8°C | 9.7°C | 44 mm | 65% | 2.9 m/s | 5.4 |
| 1991 ❄️ | 28.9°C | 23.8°C | 18.7°C | 32.9°C | 10.1°C | 102 mm | 75% | 2.2 m/s | 4.7 |
| 1990 | 31.7°C | 26.3°C | 20.9°C | 37.9°C | 12.3°C | 101 mm | 69% | 1.9 m/s | 4.9 |
| 1989 | 32.5°C | 25.4°C | 18.2°C | 39.6°C | 8.5°C | 22 mm | 54% | 2.6 m/s | 5.5 |
| 1988 | 34.6°C | 27.8°C | 20.9°C | 38.4°C | 14.4°C | 68 mm | 54% | 2.8 m/s | 5 |
| 1987 | 31.4°C | 25.3°C | 19.2°C | 35.5°C | 12.6°C | 86 mm | 67% | 2.4 m/s | 5.3 |
| 1986 | 31.0°C | 26.4°C | 21.7°C | 34.0°C | 18.4°C | 131 mm | 78% | 3 m/s | 4.7 |
| 1985 | 32.5°C | 26.3°C | 20.0°C | 41.2°C | 7.4°C | 97 mm | 62% | 3.2 m/s | 5.1 |
| 1984 | 32.2°C | 25.6°C | 19.0°C | 37.7°C | 6.8°C | 33 mm | 57% | 3.4 m/s | 4.9 |
| 1983 | 32.5°C | 26.0°C | 19.5°C | 37.9°C | 7.7°C | 38 mm | 64% | 3 m/s | — |
| 1982 | 34.1°C | 27.2°C | 20.3°C | 38.2°C | 10.8°C | 31 mm | 55% | 2.5 m/s | — |
| 1981 | 31.1°C | 25.1°C | 19.0°C | 34.6°C | 9.5°C | 73 mm | 69% | 2.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 32.7°C with lows near 20.5°C (mean 26.6°C), based on 45 years of NASA POWER data.
September averages 71 mm of rainfall in Killeen, about average for rainfall. The wettest on record was 193 mm in 2010.
The hottest September reached 44.5°C in 2000. The coldest dipped to 6.8°C in 1984.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.3°C. Daytime highs moved from 32.5°C to 35°C and overnight lows from 19.6°C to 21.6°C over the same span.
September is one of the warmer months of the year in Killeen and about average for rainfall, so plan for around 32.7°C daytime highs and 20.5°C at night.
Not quite — September is the 9th coolest month in Killeen, averaging 26.6°C.
For September in Killeen, pack light, breathable clothing and sun protection, with typical highs of 32.7°C and lows of 20.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 63% — moderately humid.
Average wind speed in September is 2.4 m/s. The windiest September on record averaged 3.4 m/s (1984).
The wettest September on record was 2010 with 193 mm. On average, September sees 71 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 Killeen 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.
