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Energy & Environment

Hey, Austin, This Heat Is Not 'Normal,' But It's Starting To Feel That Way

Woman walking in heat with umbrella to shield the sun
Gabriel C. Pérez/KUT
A woman shades herself with an umbrella while walking along South Congress Avenue.

Lee esta historia en español. 

By the end of this weekend, Austinites can expect to have sweated through more than two weeks in a row of triple-digit heat. Texas summers are supposed to be hot. But there’s nothing normal about heat waves like this one.

Temperature records for Austin go back 1898. In the first hundred years of record keeping, triple-digit heat waves lasted 10 days or longer only eight times. 

But since the turn of this century, there have been 14 such heat waves, including our current one.  If all you’ve known is Austin weather for the last 20 years, you’d be forgiven for thinking this kind of thing is normal, even though it really isn’t.

'Normal' Is Changing

Another way to look at the trends is not in terms of heat waves, but in the raw number of triple-digit days.

Victor Murphy with the National Weather Service says meteorologists look at temperature patterns in 30-year increments to determine what a statistically “average” year might look like.

From 1971 to 2000, Austin averaged just 12 triple-digit days a year. Sounds good, right?

If you move ahead one decade and look at the time between 1981 to 2010, the average number of 100-degree days goes up to 18. It’s a 50% increase, and that 30-year average has kept increasing by around 50% every 10 years since.

So far, Austin is averaging about 34 triple-digit days a year in the first 20 years of this century, up from 12 in the latter part of the 1900s.

“If we assume a 50% increase 10 years from now, that would then become a yearly average of 42 when the new 2001-2030 normals are released,” Murphy wrote to KUT in an email.

“The current 10 year normal [of triple-digit days] from 2011-2020 is indeed 42,” he added.

Can We Stop It?

Two things are causing this trend.

One is called the urban heat island effect. That's where asphalt and concrete absorb heat then radiate it back into the air. The city of Austin has programs to try to mitigate heat islands. Tree planting is one frequently used tactic.

The other cause is global warming. No amount of tree planting in Austin will help stop that without a massive international effort to reduce greenhouse gasses. If that doesn’t happen the heat could eventually become unlivable. One report out last summer forecasted that the feels-like temperatures in Austin could start to surpass 127 degrees by midcentury if world governments fail to do anything.

Correction: An earlier version of this story said that Austin had averaged 38 triple digit days a year since the turn of the century. The city has, in fact, averaged 34 triple digit days a year since that time.

Got a tip? Email Mose Buchele at mbuchele@kut.org. Follow him on Twitter @mosebuchele

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