AUSTIN (KXAN) — Austin officially hit 100° for the first time this year on Saturday, May 21. That’s the fourth-earliest we’ve ever hit the century mark in a calendar year. On June 18, we surpassed the total number of triple-digit days that we saw in 2021.
Complete temperature records for Camp Mabry — Austin’s official reporting site — date back to 1898.
Since then, Austin reached 100° a total of 1,839 times.
The chart below shows the number of triple-digit temperatures recorded each year since records began.
The summer of 2011 was record-breaking. Austin hit 100° a total of 90 times that year, including a high of 112° on August 28. That ties with Sept. 5, 2000, as the hottest temperature ever recorded in the city.
The years 1925, 2009 and 1923 all saw more than 60 days of triple-digit heat.
On the opposite end of the spectrum, Austin has failed to reach 100° in 12 different years since records began, most recently in 1987.
The average for any given year from 1898 to 2021 is about 15 triple-digit days per year.
The data shows the number of triple-digit days is increasing. Over the past 30 years, the average number of 100° days per year is about 29. The chart below shows the number recorded by decade.
While the 1920s and 1950s both stand out with a high number of triple-digit days, the first half of the century had relatively few days above 100°. Since the 1990s, the number has been increasing quickly.
The 2000s, for example, saw 273 days at or above 100°. That number increased to 409 in the 2010s.
Austin has reached the century mark on 79 days so far this decade, meaning we’ve already hit 100° more times than the entire 1930s or 1940s.
Unsurprisingly, August has recorded the most triple-digit days. The chart below shows the number of 100° days per month since records began.
Of the 1,839 days of triple-digit heat, 871 have been in August, about 47% of the total. About a third, 599, have been in July.
June has seen 219 days at or above 100° (12%) and September has seen 136 days in total (7%). May and October combined account for less than 1% of all triple-digit days since 1898.
May 4, 1984, holds the title as the earliest 100° day in a calendar year. While having an incredibly early start, the year only had 18 triple-digit days in total. Meanwhile, the latest 100° on record occurred on Oct. 2, in both 1923 and 1938.
So which calendar day has seen 100° the most? The KXAN First Warning Weather team has been keeping a daily record of weather in Austin since 1991. You can check out the Weather Diary for yourself here.
Using this data over the past 31 years, we can see which days most commonly reach the triple digits.
Aug. 10 and 12 have hit 100° a total of 19 times each, more than any other day.
The 30-year average for the first 100° day each year is July 4, while Aug. 30 is the average last triple-digit day of the year.