Weather on September 21
Round Rock, TX
55 Years of Data
Avg High
90°F
Avg Low
66°F
Warmest
2019
87°F avg
Coldest
1971
65°F avg
About This Date
September 21st in Round Rock, TX typically brings hot fall weather, with average highs around 90°F and lows near 66°F. Over 30 years of records, the warmest September 21st was in 2019 (87°F average), while the coldest was 1971 (65°F) — a 22°F range across recorded history. Rain or other precipitation has occurred on about 23% of September 21st dates historically, with the wettest September 21st recording 5.79" of rain.
Planning for September 21st in Round Rock, TX? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
1.4°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 95° | 68° | 82° | — | — |
| 2024 | 98° | 76° | 87° | — | — |
| 2023 | 97° | 72° | 84° | — | — |
| 2022 | 95° | 69° | 82° | — | — |
| 2021 | 99° | 73° | 86° | — | — |
| 2020 | 82° | 61° | 71° | 0.43" | — |
| 2019warmest | 97° | 77° | 87° | — | — |
| 2018 | 85° | 72° | 78° | 0.79" | — |
| 2017 | 93° | 75° | 84° | — | — |
| 2016 | 95° | 72° | 83° | — | — |
| 2015 | 93° | 66° | 80° | — | — |
| 2014 | 86° | 70° | 78° | — | — |
| 2013 | 77° | 64° | 71° | 5.79" | — |
| 2012 | 89° | 58° | 73° | — | — |
| 2011 | 94° | 58° | 76° | — | — |
| 2010 | 86° | 67° | 76° | 0.1" | — |
| 2009 | 92° | 67° | 79° | — | — |
| 2008 | 90° | 60° | 75° | — | — |
| 1982 | 88° | 51° | 69° | — | — |
| 1981 | 93° | 51° | 72° | — | — |
| 1980 | 95° | 74° | 84° | — | — |
| 1979 | 87° | 56° | 71° | — | — |
| 1978 | 84° | 61° | 72° | — | — |
| 1977 | 95° | 65° | 80° | — | — |
| 1976 | 85° | 63° | 74° | 2.13" | — |
| 1975 | 76° | 60° | 68° | 0.61" | — |
| 1974 | 87° | 70° | 78° | 1.02" | — |
| 1973 | 92° | 72° | 82° | — | — |
| 1972 | 95° | 70° | 82° | — | — |
| 1971coldest | 77° | 53° | 65° | — | — |
30 years of data from GEORGETOWN