Death Valley's 'world's hottest temperature' record may be due to a human error

Death Valley has held the record for the hottest air temperature ever measured near Earth's surface for 112 years, but now scientists are calling for the title to be rescinded.

According to U.S. Weather Bureau data, the air temperature at Greenland Ranch in Death Valley reached a scorching 134 degrees Fahrenheit (56.7 degrees Celsius) on July 10, 1913. This is still the highest air temperature on record, but its authenticity has been debated by meteorologists and climatologists, because — despite global warming — temperatures in the region have rarely reached 130 F (54.4 C) since 1913.

"I, along with many meteorologists and climatologists, have been quietly skeptical of the Death Valley world record our entire careers," Roy Spencer, a meteorologist and principal research scientist at the University of Alabama in Huntsville who recently led a study about Death Valley's world record status, told Live Science in an email.

For the study, Spencer and his colleagues analyzed July temperatures recorded at stations within 155 miles (250 kilometers) of Greenland Ranch between 1923 and 2024. The stations were 3,000 to 3,700 feet (910 to 1,130 meters) above sea level while Greenland Ranch is 178 feet (54 m) below sea level, so the researchers adjusted the data for elevation. (These were the closest stations to the ranch and provided the most reliable long-term data.) The team then compared the values and examined high-elevation July temperatures from 1913 to estimate the temperature at Greenland Ranch on that day.

They found that the air temperature at Greenland Ranch on July 10, 1913 was about 120 F (48.9 C), nowhere near 134 F. "The unusually hot temperatures measured at Greenland Ranch in early July 1913 are shown to be inconsistent with temperatures at surrounding stations," they wrote in the study, published Sept. 24 in the journal Bulletin of the American Meteorological Society.

Many scientists were previously skeptical about Death Valley's temperature record but few really questioned it because the World Meteorological Organization (WMO) accepted it and observations from the early 1900s with which to scrutinize the Greenland Ranch data were scarce, Spencer said.

"All deserts are hot in the summer, but Death Valley is especially hot because it is below sea level," he said. "The Death Valley record has more entertainment than climatological value, with an element of 'bragging rights' from the standpoint of tourism."

The U.S. Weather Bureau installed a station to measure temperatures at Greenland Ranch in 1911. The shelter was initially placed on the edge of an irrigated alfalfa field, but subsequent photographs suggest the ranch foreman, Oscar Denton, moved it to a hotter site above bare ground without official approval or documentation, according to the study.

Denton may have done this because ranch employees were used to measuring hotter temperatures on the ranch veranda than the station was recording and he wanted their experience to be reflected in the data, the researchers wrote. The veranda had a double roof, which may have vented hot air onto the veranda, they noted.

"While the station move away from the irrigated field would not explain the excessively hot temperature measurements, especially those in the first two weeks of July 1913, they support a pattern of straying from proper observing protocol," they wrote.

Denton may have also substituted some of the station's measurements for thermometer values on the veranda, Spencer said. "Newspaper, magazine, book accounts, and even correspondence with the Weather Bureau in San Francisco from back then show that 135 deg. F or hotter temperatures were made from that veranda using one or more thermometers of unknown provenance," he said.

The findings suggest Death Valley's world record should be rescinded, although temperatures of 130 F recorded in 2020 and 2021 might help the valley keep it, Spencer said. The period from July 2 to 18, 1913 and other years in the record also show anomalously high temperatures that should be scrutinized, the researchers noted in the study.

"I would support further investigation into this by the WMO and NOAA’s National Center for Environmental Information," said Dan McEvoy, an associate research professor of climatology at the Desert Research Institute who was not involved in the study.

The true story behind the value recorded on July 10, 1913 may never be known, but the study's conclusion that 134 F is incorrect is convincing and based on solid historical evidence, McEvoy told Live Science in an email.

"They are sampling from many surrounding stations, not just cherry picking one location," he said.