This July 4 set a record as the hottest day worldwide since 1979, the year temperatures started being recorded via satellites. That eclipsed another hottest day record set a day earlier.
While July is usually a very hot month, data from the U.S. National Centers for Environmental Prediction shows the global average temperature hit 62.92 degrees Fahrenheit on July 4.
“Not only is it the hottest time of year for the Northern Hemisphere, being the summer, but it is also globally the hottest time of year,” said Becky Bolinger, assistant state climatologist for the Colorado Climate Center at Colorado State University. “If you're going to break all-time records, those are going to be the months you're going to do it in.”
The previous record was set just a day before on July 3, with an average temperature of 62.62 degrees. The change from July 3 to 4 was a jump of 0.3 degrees – a big increase, considering it’s a global average.
Before that, the hottest average global temperature was 62.46 degrees, set in August 2016.
Bolinger said these records are not incredibly surprising.
“We know this is coming down the line," she said. "But when you do see it and realize where we've come in the past 50 years, it is a bit sobering.”
Bolinger said the recent high temps are caused by a combination of factors. Some of the biggest contributors are increased global warming and the effects ofEl Niño, a naturally-occurring climate pattern that causes the ocean's surface to warm in parts of the Pacific Ocean, thus altering weather patterns.
“The majority of our planet is ocean, and [it] has a very large heat capacity, it's very slow to change,” she said. “To have that big of a change that's largely being driven by ocean anomalies, more so even than temperature anomalies over land, just shows you that [the 0.3 degree jump] is pretty significant.”
These recent hot days are not outliers. Climate Central reports that the prevalence of extremely hot days has increased since 1970 in 195 U.S. cities. More than 70% of those cities now have at least seven more extremely hot days each year than in the ’70s.
Bolinger said it’s likely another global heat record could surpass the July 4 record if temperatures remain high later this summer.
While some Mountain West states felt the sun’s intense rays on Independence Day, other places in the region – like Colorado, Montana and Wyoming – experienced rain showers and cooler temperatures.
Bolinger emphasized the difference between climate and weather, where climate patterns occur over long periods of time while weather is short-lived. She also reminded that what’s happening weather-wise in one state may not be representative of the world.
“You can take a look at the global map and you will definitely see blue over [Colorado] as being in a cool anomaly this week,” she said. “You'll see some blues in other places, but you're also going to see a whole lot of reds.”
Still, Bolinger encourages the public not to despair over a hot day or two.
“What happens on a daily time scale is not as important as looking at that overall trend,” Bolinger said.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
