For centuries, humans have been captivated by extremes, and the quest to identify the hottest place on Earth is no exception. Is it the fiery peaks of the Flaming Mountains, as local Chinese folklore suggests, or somewhere else entirely? Ecologist Steve Running pondered this very question during a visit to the Flaming Mountain, a striking red sandstone ridge bordering the Taklimakan Desert and Tian Shan range. Local tales claim its surface sizzles between 50 to 80°C (122 to 175°F) in summer, a claim commemorated by a giant golden thermometer at a nearby tourist center. But is this truly the hottest spot, or just a scorching local legend?
Alt text: The reddish Flaming Mountains, known in local lore as China’s hottest place, prompting scientific investigation using NASA data.
Intrigued, Running and his colleagues at the University of Montana embarked on a scientific quest to pinpoint Earth’s true thermal extremes. Their research revealed a surprising truth: the title of “hottest place on Earth” is not fixed to a single location but shifts, although the conditions that create these scorching temperatures remain consistent – think arid, rocky terrains with dark surfaces.
The commonly cited record for the hottest air temperature belongs to Furnace Creek in Death Valley, California, which reached a blistering 56.7°C (134°F) in July 1913. However, this record was challenged just nine years later when El Azizia, Libya, reportedly hit 58.0°C (136.4°F) in September 1922. The World Meteorological Organization (WMO) still recognizes the El Azizia reading as the highest air temperature ever officially recorded.
Yet, according to Running, many self-proclaimed “hottest places on Earth” aren’t even in the running. This discrepancy arises partly from measurement methods and locations. To understand where the true hottest place lies, we need to delve into how temperature is measured and consider the difference between air temperature and land surface temperature.
Alt text: Map showing sparse distribution of WMO weather stations (black dots) in Earth’s hot desert regions, highlighting the need for satellite data for comprehensive temperature monitoring.
David Mildrexler, another researcher from the University of Montana, points out the limitations of ground-based measurements. “The World Meteorological Organization operates approximately 11,119 weather stations across Earth’s land surface for temperature observations,” he notes. “But when you consider the vast 144.68 million square kilometers of land, that’s only one station per 13,012 square kilometers.”
He further emphasizes the challenge of monitoring Earth’s most extreme environments: “The scorching deserts—like the Sahara, Gobi, Sonoran, and Lut—are so climatically harsh and remote that routine access for measurements and weather station maintenance becomes impractical. Consequently, the majority of Earth’s truly hottest locations are simply not directly monitored by ground instruments.”
This is where the power of satellite technology comes into play, offering a global perspective that ground stations simply cannot provide.
Air Temperature vs. Land Surface Temperature: Understanding the Difference
The phrase “it’s a hundred degrees in the shade” hints at a crucial distinction in temperature measurement. Air temperature, the reading we typically hear in weather reports, must be taken out of direct sunlight. This is because direct solar radiation can heat the thermometer and its surroundings, skewing the reading. You experience this effect personally – standing in direct sunlight feels warmer because your skin absorbs both air temperature and radiant solar energy.
Alt text: Diagram illustrating how direct sunlight elevates surface temperatures above air temperature, demonstrated by shaded areas at 40-46°F and sunny areas at 56-66°F with a 54°F air temperature.
The World Meteorological Organization standard dictates that accurate air temperature readings require thermometers positioned 1.2 to 2 meters above ground level and shielded from direct sunlight, but not shaded by structures, mountains, or trees.
Alt text: Stevenson screen, a standardized shelter used for housing thermometers and ensuring accurate air temperature measurements by shielding them from direct sunlight. (Photograph ©2006 Richard Allaway.)
In contrast, NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites measure Land Surface Temperature (LST). LST reflects the actual heating of the ground surface, where solar energy is absorbed and re-emitted. Crucially, LST is often significantly higher than air temperature. Anyone who has walked barefoot on hot sand or pavement understands this difference – the surface feels far hotter than the surrounding air.
This difference was scientifically observed as early as 1915. Researchers near Tucson, Arizona, during the time of the Death Valley air temperature record, measured a soil temperature of 71.5°C (160.7°F) just 0.4 centimeters below the surface, while the air temperature at four feet above ground was a much lower 42.5°C (108.5°F).
Air temperature is moderated by atmospheric circulation and moisture, representing the temperature felt by living organisms and structures. Land surface temperature, however, reveals the raw heating of the ground by solar radiation and other heat sources. The highest LSTs occur in areas with clear skies, dry soil, and minimal wind. The surface composition also plays a vital role – dark, rocky deserts with low albedo (low reflectivity) are ideal for maximizing heat absorption.
Alt text: Dark pebbles covering the Lut Desert in Iran, contributing to its status as one of the hottest places on Earth due to high heat absorption. (Photograph ©2005 Jafar Sabouri, Geological Survey of Iran.)
Satellite Data Pinpoints the Lut Desert
Running, Mildrexler, and Maosheng Zhao analyzed years of global MODIS LST data from 2003 to 2009, focusing on barren and sparsely vegetated areas. Their analysis consistently pointed to the Lut Desert in Iran as the hottest spot on Earth. They also identified Queensland, Australia, and the Flaming Mountain region as other contenders.
Alt text: Landsat satellite image of the Turpan Depression near the Flaming Mountain in China, showcasing diverse surface features and temperature variations.
Alt text: Temperature map of the Turpan Depression and Flaming Mountain area, derived from Landsat 7 data, revealing hotter temperatures in the Shanshan dune field. (NASA images by Jesse Allen and Robert Simmon, using Landsat 7 data from the USGS Global Visualization Viewer.)
For five out of the seven years studied (2004, 2005, 2006, 2007, and 2009), the Lut Desert recorded the highest surface temperature globally. In 2005, it reached a scorching peak of 70.7°C (159.3°F), significantly hotter than the official air temperature record. While the Lut Desert dominated, Queensland, Australia, held the top spot in 2003 with 69.3°C (156.7°F), and the Flaming Mountain area peaked in 2008 at 66.8°C (152.2°F).
Alt text: Global map of average daytime land surface temperatures from 2003-2009, derived from MODIS data, highlighting the Lut Desert as the consistently hottest region. (NASA maps by Jesse Allen and Robert Simmon, using MODIS data from Mildrexler et al., 2011.)
Land Surface Temperature: More Than Just Trivia
Understanding land surface temperature is crucial beyond mere curiosity. LST is directly linked to how humans use and alter the land. Climatologist Roger Pielke Sr. explains, “The hottest temperatures were observed at locations devoid of vegetation. This implies that land changes leading to reduced vegetation cover will likely result in hotter maximum surface temperatures. Conversely, developing an oasis in a desert through irrigation would lower maximum temperatures.”
The Pacific Northwest region of the United States provides a compelling example of this relationship. With its dramatic ecological gradient from coast to rainforest to desert within a short distance, it perfectly illustrates how land cover influences heat absorption and radiation.
Alt text: Natural-color satellite image of the Pacific Northwest, showcasing diverse landscapes from forests to arid regions and their impact on surface temperatures.
Alt text: Map of daytime land surface temperatures in the Pacific Northwest, revealing cooler temperatures in forested areas and warmer temperatures in barren and arid landscapes. (NASA images by Jesse Allen and Robert Simmon, using MODIS data.)
Coastal forests, with their deep-rooted trees accessing soil moisture and cooling through transpiration, exhibit land and air temperatures that are closely aligned. Moving inland to farmland and grasslands, where soil moisture is less available and plant roots are shallower, the temperature difference widens. Finally, the arid inland deserts experience extreme temperature swings, heating up dramatically during the day and cooling significantly at night.
Mildrexler and Running suggest that long-term LST records can serve as a valuable tool for tracking land cover changes, including deforestation, urbanization, and irrigation. Rising LSTs over time may indicate shifts in land use patterns. Deforestation, for instance, leads to increased land surface temperatures as forests are significantly cooler than cleared land. Conversely, irrigated crops can be cooler than natural vegetation due to evaporative cooling.
Urban Heat Islands: Unexpected Hotspots
Cities, often overlooked in the search for the hottest place, can rival deserts in surface temperature extremes. Stuart Gaffin, a climate researcher at Columbia University and NASA’s Goddard Institute for Space Studies, observes, “I routinely see surface temperatures in cities exceeding those found in deserts.”
Gaffin studies the urban heat island effect, where cities trap heat and become significantly warmer than surrounding rural areas. The U.S. Environmental Protection Agency estimates that urban air temperatures can be up to 6°C (10°F) higher than in surrounding areas.
Alt text: Satellite temperature map of Shanghai, China, illustrating the urban heat island effect with significantly higher temperatures in the city center compared to surrounding areas. (Map by Jesse Allen and Robert Simmon, using Landsat 7 data from the USGS Global Visualization Viewer.)
However, standard satellite LST data with resolutions around 5.6 square kilometers are often too coarse to capture the fine-scale temperature variations within cities, where shadows from buildings and vegetation can lower average LST readings.
To overcome this, Gaffin uses portable infrared radiometers in New York City. His measurements have revealed rooftop temperatures on black tar-paper roofs reaching a staggering 77 to 82°C (170 to 180°F) in mid-summer, intensifying the summer heat through radiant heat emission, day and night. Even in winter, rooftops can be significantly warmer than air temperatures.
Alt text: Satellite image of the Con Edison building in Long Island City, New York, a site for urban heat island research comparing temperatures of different roof types. (Images by Robert Simmon, using data ©2010 DigitalGlobe and from the Columbia University Center for Climate Systems Research.)
Gaffin’s research focuses on mitigating urban heat islands by modifying rooftops and other impervious surfaces to reflect more sunlight. New York City alone has over 77 square kilometers of tar-paper rooftops, acting as “tar beaches” that absorb and radiate heat. Similarly, synthetic turf fields, while aesthetically resembling grass, lack the cooling capacity of natural vegetation and can reach skin-burning temperatures comparable to black pavement.
Solutions like white roofs and green roofs (vegetated rooftops) offer effective ways to combat urban heat. Even simply painting black roofs white can dramatically reduce surface temperatures.
Alt text: Green roof on top of the Con Edison building in Queens, New York, demonstrating a sustainable solution to reduce urban heat island effect and lower surface temperatures. (Photograph ©2008 Con Edison of New York.)
With over half the world’s population residing in cities, the combined effects of urban heat islands and global warming pose a significant challenge. Finding ways to make cities more habitable in the face of rising temperatures is becoming increasingly critical for energy conservation and quality of life. Understanding land surface temperature and its drivers is a vital step in addressing this challenge and creating cooler, more sustainable urban environments.
