AUSTIN (KXAN) — Much of the focus during the summer months is on extreme heat during the daytime. However, our warming climate is also increasing nighttime temperatures.
KXAN’s climate partners at Climate Central released a study that found that since 1970, summer nights have warmed by an average of about 3 degrees.
Their analysis took numbers from 247 United States cities. Nearly all of them saw an increase in nighttime temperatures.
On average, these cities currently experience about 27 warmer-than-normal summer nights with a strong climate change fingerprint each year, compared to one such day annually during the 1970s, according to the study.
The sweltering nights limit the ability of our bodies to adequately cool off and recover from the daytime heat. This raises the risk of heat stress and other serious health impacts, especially when combined with those hot summer days.
The First Warning Weather Team has stressed many times over the years that heat is the deadliest weather-related hazard in our country. The warmer-than-normal nights can worsen heat stress and other health risks in summer.
Photo courtesy of the National Weather Service
Heat claimed 199 lives in 2024. That’s more than double the cause of the second-most weather-related deaths: floods. Flooding claimed 89 lives in 2024.
The study done by Climate Central analyzed 241 U.S. locations that took into account summer minimum temperatures. The data from 1970 to 2024 found that these summer temps increased by an average of 3.1 degrees in 231 of the 241 cities.
The analysis revealed that, when combined, these cities experienced nearly 27 warmer-than-normal morning lows between 2020 and 2024.
The region with the highest summer nighttime warming is the southwest. Since 1970, 11 cities have seen summer nights warm by an eye-popping average of 4.5 degrees.
The map above illustrates that the average yearly warm summer nights were made at least twice as likely by climate change.
The trend in Austin shows that the capital center was on par with the national average of a little more than 3 degrees.
Courtesy: Climate Central
Going back to 1970, you will see the average low temperature in the summer time was between 72 and 73 degrees. That number has steadily increased by 3.1 degrees to numbers that averaged around 76 degrees in 2024.
Summer mornings can also see higher numbers for minimum temperatures.
The current average of morning lows (30-year data from 1991-2020) reflects these monthly low temperature averages:
- 72.9° in June
- 75.0° in July
- 75.1° in August
The average of those three months is 74.3 degrees.
In 2024 alone, the average low temperature was warmer, at 76.1 degrees.
Courtesy: Climate Central
The number of sweltering nights has gone up appreciably in Austin since the 70s. The graph above illustrates how climate change has made warmer nights (daily minimum temperatures) twice as likely, with more than 40 nights of high heat.
Austin’s increase of more than 40 nights did not come remotely close to the Top Five list. It’s interesting to note that the Top Five locations were all in Florida. West Palm Beach topped this list with 62 nights, followed by Ft. Myers (61), Miami (60), Tampa (59), and Orlando (58).