September is one of the warmer months of the year in Mckinney, with average highs near 32.3°C and lows around 19.9°C (mean 26.1°C). It is about average for rainfall, averaging 71 mm of rainfall and 61% relative humidity across the period.
September is one of the warmer months of the year in Mckinney. Across 45 years of records, the warmest September in Mckinney was 2019 — when the month averaged 30.4°C — while the coldest was 1991 at 23.1°C. Typical September days reach 32.3°C with nights near 19.9°C. The long-term trend is warming, about 0.5°C per decade.
September is about average for rainfall in Mckinney, averaging 71 mm of rainfall. The wettest September on record was 2010 with 202 mm, while the driest was 2019 at 12 mm.
Relative humidity in Mckinney during September averages 61%. The most humid September was 2018 at 78%, and the least humid was 2011 at 41%.
September receives about 5.1 kWh/m²/day of solar energy in Mckinney. The sunniest September was 2022 at 5.9 kWh/m²/day, and the cloudiest was 2018 at 4.
Average wind speed in Mckinney during September is 2.6 m/s. The windiest Septembers were 1984 and 1985 at 3.5 m/s, while the calmest was 2025 at 1.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 25.5°C | 25.7°C | 25.5°C | 27.1°C | 27.0°C | +1.5°C |
| Avg High | 31.8°C | 31.8°C | 31.6°C | 33.1°C | 33.4°C | +1.6°C |
| Avg Low | 19.2°C | 19.6°C | 19.4°C | 21.1°C | 20.5°C | +1.3°C |
| Avg Rain | 73 mm | 73 mm | 70 mm | 75 mm | 60 mm | -13 mm |
September temperatures in Mckinney have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 5.2°C (1984) to a record high of 45°C (2000).
Rainfall in September is about average for rainfall, averaging 71 mm, with a wettest year of 202 mm.
One of the best times to visit Mckinney
September is one of the best times to visit Mckinney. Expect days averaging 32.3°C and nights around 19.9°C (mean 26.1°C) — warmer than Mckinney'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 | 33.7°C | 27.1°C | 20.4°C | 39.1°C | 15.6°C | 55 mm | 58% | 1.9 m/s | 5.5 |
| 2024 | 32.8°C | 26.5°C | 20.1°C | 39.2°C | 13.2°C | 95 mm | 61% | 2.2 m/s | 5.3 |
| 2023 | 36.0°C | 29.5°C | 23.1°C | 44.8°C | 19.4°C | 42 mm | 52% | 2.5 m/s | 5.1 |
| 2022 | 33.5°C | 26.9°C | 20.3°C | 37.2°C | 13.2°C | 26 mm | 59% | 2.1 m/s | 5.9 |
| 2021 | 34.9°C | 27.8°C | 20.7°C | 39.7°C | 13.2°C | 20 mm | 51% | 2.3 m/s | 5.7 |
| 2020 | 29.7°C | 24.2°C | 18.6°C | 35.0°C | 10.2°C | 122 mm | 74% | 2.7 m/s | 4.6 |
| 2019 🔥 | 36.6°C | 30.4°C | 24.2°C | 39.7°C | 22.1°C | 12 mm | 56% | 2.9 m/s | 5.4 |
| 2018 | 30.1°C | 25.8°C | 21.5°C | 37.2°C | 13.5°C | 196 mm | 78% | 2.2 m/s | 4 |
| 2017 | 32.7°C | 26.3°C | 20.0°C | 36.8°C | 14.6°C | 27 mm | 62% | 2.6 m/s | 5.5 |
| 2016 | 32.0°C | 26.5°C | 20.9°C | 36.8°C | 11.5°C | 77 mm | 69% | 2.2 m/s | 5.5 |
| 2015 | 34.5°C | 28.2°C | 21.8°C | 39.4°C | 17.1°C | 29 mm | 56% | 2.5 m/s | 5.5 |
| 2014 | 32.6°C | 26.7°C | 20.8°C | 39.1°C | 13.3°C | 29 mm | 63% | 2.4 m/s | 5 |
| 2013 | 34.2°C | 28.0°C | 21.9°C | 41.2°C | 12.8°C | 79 mm | 54% | 2.3 m/s | 5.3 |
| 2012 | 33.3°C | 26.7°C | 20.0°C | 41.6°C | 13.1°C | 64 mm | 55% | 2.6 m/s | 5.2 |
| 2011 | 34.1°C | 26.7°C | 19.4°C | 42.3°C | 12.2°C | 30 mm | 41% | 2.8 m/s | 5.8 |
| 2010 🌧️ | 30.6°C | 25.5°C | 20.5°C | 35.2°C | 10.4°C | 202 mm | 73% | 2.6 m/s | 5 |
| 2009 | 28.9°C | 23.9°C | 18.9°C | 37.2°C | 11.8°C | 180 mm | 74% | 2.6 m/s | 4.2 |
| 2008 | 30.5°C | 24.4°C | 18.3°C | 34.9°C | 11.2°C | 50 mm | 68% | 2.5 m/s | 5.1 |
| 2007 | 30.2°C | 25.1°C | 20.1°C | 32.6°C | 15.9°C | 98 mm | 76% | 2.2 m/s | 5 |
| 2006 | 31.4°C | 24.7°C | 18.0°C | 36.9°C | 11.5°C | 59 mm | 59% | 2.7 m/s | 5.3 |
| 2005 | 36.2°C | 29.2°C | 22.3°C | 40.4°C | 16.6°C | 22 mm | 50% | 2.8 m/s | 5.5 |
| 2004 | 32.2°C | 25.8°C | 19.3°C | 36.5°C | 13.3°C | 31 mm | 61% | 2.3 m/s | 5.5 |
| 2003 | 29.5°C | 23.8°C | 18.0°C | 34.1°C | 13.1°C | 97 mm | 68% | 2.3 m/s | 4.7 |
| 2002 | 33.3°C | 26.7°C | 20.1°C | 37.7°C | 12.4°C | 45 mm | 58% | 2.5 m/s | 5.3 |
| 2001 | 28.9°C | 23.7°C | 18.5°C | 32.8°C | 10.2°C | 90 mm | 73% | 2.4 m/s | 4.9 |
| 2000 | 34.5°C | 27.3°C | 20.1°C | 45.0°C | 8.7°C | 24 mm | 45% | 2.8 m/s | 5.4 |
| 1999 | 32.7°C | 25.9°C | 19.1°C | 37.9°C | 9.9°C | 47 mm | 51% | 3.1 m/s | 5.3 |
| 1998 | 34.8°C | 29.0°C | 23.1°C | 43.6°C | 18.9°C | 68 mm | 62% | 2.7 m/s | 5 |
| 1997 | 35.0°C | 28.1°C | 21.3°C | 39.1°C | 14.2°C | 19 mm | 51% | 2.8 m/s | 5.2 |
| 1996 | 29.0°C | 23.4°C | 17.8°C | 33.2°C | 8.6°C | 84 mm | 71% | 2.2 m/s | 4.8 |
| 1995 | 31.2°C | 25.3°C | 19.4°C | 41.3°C | 7.4°C | 99 mm | 64% | 2.8 m/s | 4.4 |
| 1994 | 30.5°C | 24.2°C | 17.9°C | 35.7°C | 8.4°C | 76 mm | 65% | 2.4 m/s | 5 |
| 1993 | 32.1°C | 25.2°C | 18.3°C | 37.4°C | 9.3°C | 105 mm | 60% | 2.8 m/s | 5.4 |
| 1992 | 31.5°C | 25.2°C | 18.8°C | 35.9°C | 9.0°C | 97 mm | 67% | 2.9 m/s | 5 |
| 1991 ❄️ | 28.2°C | 23.1°C | 18.0°C | 32.6°C | 8.3°C | 81 mm | 75% | 2.4 m/s | 4.7 |
| 1990 | 33.4°C | 27.6°C | 21.8°C | 41.0°C | 10.1°C | 50 mm | 61% | 2.3 m/s | 4.9 |
| 1989 | 29.8°C | 23.4°C | 17.0°C | 40.3°C | 6.3°C | 88 mm | 63% | 2.6 m/s | 5.2 |
| 1988 | 32.3°C | 25.7°C | 19.2°C | 36.8°C | 13.4°C | 132 mm | 62% | 2.6 m/s | 5 |
| 1987 | 31.5°C | 25.1°C | 18.6°C | 36.1°C | 12.3°C | 80 mm | 63% | 2.4 m/s | 5.2 |
| 1986 | 31.1°C | 26.2°C | 21.3°C | 34.7°C | 14.5°C | 126 mm | 75% | 3.4 m/s | 4.6 |
| 1985 | 32.3°C | 26.1°C | 19.9°C | 42.5°C | 5.7°C | 87 mm | 56% | 3.5 m/s | 5.1 |
| 1984 | 31.9°C | 25.3°C | 18.6°C | 38.5°C | 5.2°C | 34 mm | 53% | 3.5 m/s | 4.9 |
| 1983 | 33.2°C | 26.4°C | 19.6°C | 37.1°C | 8.0°C | 17 mm | 57% | 3.2 m/s | — |
| 1982 | 32.8°C | 26.0°C | 19.2°C | 39.1°C | 9.6°C | 23 mm | 53% | 2.9 m/s | — |
| 1981 | 31.6°C | 25.3°C | 19.1°C | 34.7°C | 9.0°C | 70 mm | 63% | 2.6 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 19.9°C (mean 26.1°C), based on 45 years of NASA POWER data.
September averages 71 mm of rainfall in Mckinney, about average for rainfall. The wettest on record was 202 mm in 2010.
The hottest September reached 45°C in 2000. The coldest dipped to 5.2°C in 1984.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 32.4°C to 34.2°C and overnight lows from 19.3°C to 20.9°C over the same span.
September is one of the warmer months of the year in Mckinney and about average for rainfall, so plan for around 32.3°C daytime highs and 19.9°C at night.
Not quite — September is the 9th coolest month in Mckinney, averaging 26.1°C.
For September in Mckinney, pack light, breathable clothing and sun protection, with typical highs of 32.3°C and lows of 19.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 61% — moderately humid.
Average wind speed in September is 2.6 m/s. The windiest September on record averaged 3.5 m/s (1984).
The wettest September on record was 2010 with 202 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 Mckinney 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.
