Austin has had 48 triple-digit days so far this year. That puts this summer on track to be the third hottest ever recorded in the city in terms of average temperature. It also continues a trend of warming in the region that became more pronounced around the turn of the century.
“Definitely when you look at the record hottest years, the majority of the top 10 have occurred in the last 20 years or so,” says Brett Williams, a meteorologist with the National Weather Service.
Williams expects Austin to finish off August with an average summer temp of 87.6 degrees. The only two summers hotter than that were in 2009 and 2011.
When it comes to the number of triple-digit days in a year, 2018 currently ranks sixth. But there are still plenty of days left to push the city higher up the list.
Both metrics – days of high heat and average temperature – tell the story of a warming city. For example, last century Austin averaged around 13 triple days a year. This century it's averaging around 33 a year.
The reasons for the rise in temperature include the urban heat island effect, which is caused by buildings and pavement absorbing more heat than the surrounding land, and greenhouse gas emissions warming up the atmosphere.