Climate averages 1991–2020
Round Rock weather
in September.
A hot, moderately wet month: the 4th warmest and the joint 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Round Rock: daytime highs average 31.1°C and nights cool to about 21.5°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 74 mm of rain on roughly 7 days, which makes September a moderately wet month (the joint 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 23 min on an average September day.
The nearest other city in this atlas is Austin (28 km away). In September its highs average 31.3°C, about as warm as Round Rock, with 75 mm of rain.
Among the 498 cities listed in the United States, Round Rock ranks joint 53rd of 498 for the warmest September highs and joint 241st of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Round Rock is 4.2°C warmer than that mean.
From September to October, average highs fall by 4.7°C to 26.4°C, and monthly rainfall rises from 74 mm to 86 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
Round Rock climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 15.6°C5.8°C | 5.8°C | 59 | 6.8 | 10.410 h |
| February | 17.8°C7.6°C | 7.6°C | 61 | 7.4 | 11.111 h |
| March | 21.4°C11.0°C | 11.0°C | 74 | 8.8 | 12.012 h |
| April | 25.5°C14.9°C | 14.9°C | 76 | 8.2 | 12.913 h |
| May | 28.9°C19.3°C | 19.3°C | 110 | 10.8 | 13.714 h |
| June | 32.4°C22.7°C | 22.7°C | 72 | 8.7 | 14.114 h |
| July | 34.5°C24.2°C | 24.2°C | 39 | 5.7 | 13.914 h |
| August | 34.7°C24.6°C | 24.6°C | 54 | 5.8 | 13.313 h |
| September, selected | 31.1°C21.5°C | 21.5°C | 74 | 7.4 | 12.412 h |
| October | 26.4°C16.4°C | 16.4°C | 86 | 7.1 | 11.511 h |
| November | 20.3°C10.8°C | 10.8°C | 69 | 6.6 | 10.611 h |
| December | 16.3°C6.8°C | 6.8°C | 70 | 7.5 | 10.210 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
- Austin in SeptemberUnited States · 28 kmHigh 31.3°C · Low 21.8°C · 75 mm rain
- Killeen in SeptemberUnited States · 68 kmHigh 30.8°C · Low 21.3°C · 69 mm rain
- Temple in SeptemberUnited States · 73 kmHigh 31.0°C · Low 21.4°C · 69 mm rain
- New Braunfels in SeptemberUnited States · 99 kmHigh 31.3°C · Low 21.8°C · 74 mm rain
- Waco in SeptemberUnited States · 126 kmHigh 31.4°C · Low 21.7°C · 60 mm rain
- Bryan in SeptemberUnited States · 127 kmHigh 31.4°C · Low 21.8°C · 76 mm rain
- College Station in SeptemberUnited States · 129 kmHigh 31.4°C · Low 21.8°C · 76 mm rain
- San Antonio in SeptemberUnited States · 144 kmHigh 31.6°C · Low 22.0°C · 77 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 Round Rock) is explained once on the Round Rock year overview and on the Sources, method and limits page.