The triple-digit heatwave hitting Austin is becoming one for the record books. On Wednesday, it became the fifth longest ever recorded in the city's history, and more hot days are expected.

It’s part of a trend. Thanks to global warming and the heat island effect, Austin is getting much hotter. Now, a new report shows just how it ranks against other U.S. cities when it comes to rising temperatures.

Climate Central, a group that promotes awareness of global warming, took data from the National Weather Service on how often U.S. cities hit a heat index of 90 degrees or higher. It found that out of 239 cities, 198 have seen a jump in the average number of those days, called “extreme heat days,” annually since 1979.

Austin’s increase in extreme heat days was the ninth biggest among U.S. cities. The report says the city now has about 22 more days that feel like 90 degrees or higher each year than it did before 1979.

The report also points out that “extreme heat now extends well beyond the summer months.” Austin, for example, had 126 such days on average over the last five years.

Three other Texas cities, McAllen, Tyler and Corpus Christi made the Top 10 list.

Austin also ranked ninth in the increase in dangerously hot days nationally. According to the report those occur “when the combination of heat and humidity makes it feel like it’s 105°F or hotter.”

Four other Texas cities made it to the Top 10 of that list: McAllen, Laredo, Victoria and Houston.

The report from Climate Central follows a study released by the Union of Concerned Scientists that looked at climate trends and found the heat in Austin could outpace science's ability to measure it by 2036.

That report found if nothing is done about climate change, Austin may average one day a year where the feels-like temperature hits 127 degrees by the middle part of the century – anywhere from 2036 to 2065. That would rise to 12 days, on average, by the end of the century – between 2070 and 2099.

Both these studies look at the heat index, or “feels like” temperature. But Austin is also seeing a dramatic increase in simple thermometer temperature.

When it comes to triple-digit days, last century Austin averaged about 13 annually. This century, we’re averaging 38 triple-digit days a year, according to Spectrum News Chief Meteorologist Burton Fitzsimmons.

He says the average annual temperature is 4 degrees warmer today than it was 40 years ago.