As September begins, Austin is nearing the end of its triple-digit temperature days, with the average final 100ºF day typically occurring on August 30. However, 2025 has seen 19 triple-digit highs at Camp Mabry through September 2, fewer than the record-breaking 68 and 80 days in 2022 and 2023, respectively, and below the average of 29 days. Despite this, September can still bring heat, with an average of three triple-digit days and a potential high this week.

Austin's climate is warming, with the average number of triple-digit days rising from 10 per year (1961-1990) to 29 (1991-2020), partly due to climate change and urban growth. Recent years have seen late triple-digit days, including mid-October last year, the latest on record. The First Warning Weather Team continues to monitor for signs of cooler fall weather.