Climate averages 1991–2020
McKinney weather
in September.
A hot, moderately wet month: the 4th warmest and the 5th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in McKinney: daytime highs average 30.0°C and nights cool to about 20.9°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 78 mm of rain on roughly 7 days, which makes September a moderately wet month (the 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 24 min on an average September day.
The nearest other city in this atlas is Allen (12 km away). In September its highs average 30.0°C, about as warm as McKinney, with 71 mm of rain.
Among the 498 cities listed in the United States, McKinney ranks joint 126th of 498 for the warmest September highs and joint 268th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; McKinney is 3.1°C warmer than that mean.
From September to October, average highs fall by 5.6°C to 24.4°C, and monthly rainfall rises from 78 mm to 104 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
McKinney climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 12.2°C3.0°C | 3.0°C | 70 | 6.8 | 10.210 h |
| February | 14.7°C5.0°C | 5.0°C | 74 | 7.6 | 11.011 h |
| March | 18.8°C8.9°C | 8.9°C | 105 | 9.4 | 12.012 h |
| April | 23.1°C13.1°C | 13.1°C | 118 | 9.1 | 13.013 h |
| May | 27.1°C18.1°C | 18.1°C | 144 | 11.5 | 13.914 h |
| June | 31.2°C22.4°C | 22.4°C | 91 | 9.1 | 14.314 h |
| July | 33.8°C24.8°C | 24.8°C | 50 | 6.2 | 14.114 h |
| August | 33.9°C24.8°C | 24.8°C | 50 | 5.8 | 13.413 h |
| September, selected | 30.0°C20.9°C | 20.9°C | 78 | 6.8 | 12.412 h |
| October | 24.4°C14.9°C | 14.9°C | 104 | 7.9 | 11.411 h |
| November | 17.9°C8.9°C | 8.9°C | 94 | 7.2 | 10.510 h |
| December | 13.1°C4.3°C | 4.3°C | 94 | 7.2 | 10.010 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Allen in SeptemberUnited States · 12 kmHigh 30.0°C · Low 21.0°C · 71 mm rain
- Frisco in SeptemberUnited States · 20 kmHigh 29.9°C · Low 20.8°C · 81 mm rain
- Plano in SeptemberUnited States · 21 kmHigh 30.1°C · Low 21.0°C · 71 mm rain
- Richardson in SeptemberUnited States · 30 kmHigh 30.2°C · Low 21.1°C · 71 mm rain
- Garland in SeptemberUnited States · 32 kmHigh 30.3°C · Low 21.1°C · 71 mm rain
- Carrollton in SeptemberUnited States · 37 kmHigh 30.4°C · Low 21.4°C · 72 mm rain
- Lewisville in SeptemberUnited States · 39 kmHigh 30.4°C · Low 21.4°C · 72 mm rain
- Mesquite in SeptemberUnited States · 48 kmHigh 30.6°C · Low 21.3°C · 64 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for McKinney) is explained once on the McKinney year overview and on the Sources, method and limits page.