It is based on a location...

The fight over Death Valley's 134-degree temperature record heats up

Amy Graff

On July 10, 1913, Oscar Denton, a U.S. Weather Bureau observer stationed at Greenland Ranch, in Death Valley, California, claimed the mercury hit an astonishing 134 degrees Fahrenheit, the highest temperature ever recorded in the United States. In 2012, Denton’s record was officially recognized as the world heat record by the United Nations’ World Meteorological Organization, the international arbiter of weather records. 

For years, though, a small group of weather-watchers have called the legitimacy of Denton’s claim into question, citing the observer’s inexperience and the much less dramatic temperatures recorded at nearby stations that day. Now, as the world warms, more experts are beginning to look critically at the record — including UCLA climate scientist Daniel Swain, whose Twitter and YouTube coverage of California’s weather have made him a minor celebrity.

“There are plenty of reasons to be skeptical that this reading is valid,” including the quality of Denton’s records, Swain wrote in an email to SFGATE. Indeed, when recently referring to the Death Valley temperature record in his blog, he didn’t refer to the 1913 record. Instead, he uses 130 degrees as the benchmark. Swain considers this “the highest reliable reading, i.e., with no known data quality issues,” he said in an email. 

The World Meteorological Organization has investigated and overturned long-held records before. Indeed, until 2012, the world heat record was officially held by a small town in Libya, where an observer in 1922 claimed the temperature hit 58 degrees Celsius, or about 136 degrees Fahrenheit. The WMO put Denton’s record back on top in 2012, after a painstaking investigation by experts from nine countries found the Libyan record unreliable, citing five main issues including “problematical instrumentation” and “a likely inexperienced observer.” 

Swain admits that questions about the Death Valley record could be dismissed as trivia, immaterial to modern climate science. But record-setting weather gets a lot of attention, and has dire consequences, including destroying natural ecosystems, damaging communities and causing death.

“Given how much play this number gets in the popular press and broadly in society, I’d say that it’s now probably worth the WMO committee’s time to take a formal look at whether it’s truly plausible given what has come to light through informal investigations over the past decade,” Swain wrote.

With or without the 1913 record, Death Valley is widely considered the hottest place on Earth. The barren, sandy expanse spans 156 miles from north to south, in the driest part of California’s Mojave Desert. Mountains ring the valley, trapping heat that bakes the valley floor so hot it can cause third-degree burns on bare feet. In the summer, air temperatures frequently soar into the 120s, and hit 130 degrees once each in both 2020 and 2021, the two scorching days Swain cites as the hottest "reliable reading" ever recorded at Death Valley. (The WMO said it is "currently verifying" the two readings.)

“If you have ever opened the oven to check on your cookies and that blast of warm air you feel, it can feel like that in Death Valley,” said Ashley Nickerson, a meteorologist with the weather service’s Las Vegas office, which oversees the Death Valley weather station.

The U.S. Weather Bureau (now called the National Weather Service) first began recording Death Valley temperatures in 1911, at the now-defunct Greenland Ranch. Denton was the caretaker and foreman at the ranch between 1912 and 1920, tending to a 40-acre plot of alfalfa and figs with the help of the local Panamint Indians. He was also tasked with running the Weather Bureau’s station, including taking daily temperature readings. 

On the day Denton logged the 134-degree record, he was still relatively new to the job. And according to California climatologist and storm chaser William T. Reid, who has taken a decadeslong deep dive into Denton’s logs, there’s evidence in the erratically kept records that Denton may have ignored standard procedures. 

“The records he kept weren’t very good,” Reid told SFGATE. "He cooked the books."

Reid explained in an email, "In the warm months leading up to July, 1913, there are a handful of instances in which the daily maximum temperature at Greenland Ranch appears too warm, by 5 to 10 degrees perhaps, compared to the maximums at the closest surrounding stations."

The anomalous maximums culminated in early July, Reid said, when Denton logged an improbable five consecutive readings of 129 or above the week he recorded the record-setting high, including 130 degrees on July 12 and 131 on July 13, as well as 134 degrees on July 10. 

Christopher Burt, an Oakland-based weather historian who has worked with Reid to analyze the data, has looked at the temperatures recorded at nearby locations on July 10, 1913. Based on historical correlations, Burt believes the temperature in Death Valley on July 10 likely could not have been higher than 125 degrees.

“It’s virtually impossible that Death Valley hit 134” that day, said Burt, who was part of the team that decertified the 1922 Libya record. "134 is way out there, it’s way offline."

Swain agrees. “The large-scale meteorological pattern and the overall heat of the air mass in the Southwest when the 1913 record purportedly occurred does not appear to be capable of generating such extreme temperatures in Death Valley short of a truly exceptional and highly localized event,” he wrote in an email.

Burt has asked the WMO and the National Climate Extremes Committee to review the 1913 record. The international agency has certainly been known to dig deep when it wishes; the investigation into the Libyan record involved tracking down the original log book shortly before the country’s 2011 civil war, which briefly interrupted the inquiry. But Burt isn’t holding his breath over the Death Valley case. The investigations are extremely time- and labor-intensive, he knows, and no one has published a peer-reviewed article calling the record into question, which makes the criticism easier to dismiss. 

“​​The participants aren’t fully compensated and so they don’t take on these investigations lightly,” said Burt, who is also the author of the 2007 book “Extreme Weather: A Guide and Record Book.” “They want to make sure it’s worth their time and effort.”

Randall Cerveny, the WMO’s rapporteur on weather and climate extremes, agreed that the organization would need significantly more evidence of an error than the records of nearby climate stations registering less extreme temperatures on July 10, 1913.

“That claim was at least partially debunked even back in 1949 by noted California state climatologist Arnold Court who postulated that perhaps a dust storm with downburst winds may have influenced that observation locally but not regionally,” Cerveny, who teaches geographical sciences at Arizona State University, wrote in an email. “The 1913 record stands until clear, new evidence is presented for re-examining it.”

Skeptics of the Death Valley record are unlikely to find an ally at the National Weather Service; in response to questions about Denton’s record, a spokesperson told SFGATE, “134 degrees on July 10 in 1913 remains the world-record until the WMO states otherwise.”

Even if the WMO ever did investigate, and overturn, Denton’s record, it wouldn’t necessarily be the end of Death Valley as the “hottest place on Earth.” Burt, at least, has little faith in the only official record that tops Death Valley’s well-documented 130 degree days: A measurement of 131 degrees, recorded on July 7, 1931, at a colonial weather station in Kebili, Tunisia.

As Burt told Yale’s climate blog in 2021, “the Kebili ‘record’ is even more bogus than even the [Libyan] record. … Kebili is a relatively cool spot in Tunisia (an oasis) and never since the 1930s ever again recorded a maximum temperature above 118 degrees Fahrenheit. Nowhere in Africa has any reliably observed temperature been measured above 126 degrees Fahrenheit.”