The question of Earth’s warmest region is complicated because the answer depends entirely on the metric used. Scientists must differentiate between a single, momentary heat peak and the relentless, sustained warmth measured over an entire year. To accurately categorize these extreme environments, measurements focus on maximum air temperature, ground temperature, or the long-term average temperature. The physical conditions that create a brief, record-breaking spike are often different from those that produce high temperatures day after day.
Defining the Hottest Regions
Meteorologists and climatologists use precise criteria to define and compare extreme heat across the globe. The most commonly cited measurement is the maximum air temperature, taken in the shade, typically 1.5 meters (4 feet 11 inches) above the ground. This standardized method provides a consistent benchmark for a location’s peak heat capacity.
A single record reading, however, does not convey the climate of a region over time. A more descriptive metric is the annual mean temperature, which is the average of daily temperatures over an entire year. This figure captures the sustained, year-round warmth of a location. Furthermore, satellite technology can measure land surface temperature (LST), which records the heat radiating from the ground itself, often resulting in far higher numbers than air temperature readings.
Regions with the Highest Recorded Temperatures
The official record for the highest air temperature ever measured belongs to Furnace Creek in Death Valley, California, USA. On July 10, 1913, the thermometer registered a peak of 56.7°C (134°F), a measurement recognized by the World Meteorological Organization (WMO). This record solidified Death Valley’s reputation as the single hottest spot on the planet based on air readings.
For a period, a reading of 58.0°C (136.4°F) from El Azizia, Libya, taken in 1922, was considered the world record. However, the WMO officially disqualified this record in 2012 after an investigation found significant errors in the measurement. More recently, Death Valley has continued to push the limits, recording temperatures of 54.4°C (129.9°F) in both 2020 and 2021. These readings are currently undergoing official validation but represent the highest verifiable temperatures of the modern era.
Regions with the Highest Sustained Average Temperatures
Regions defined by their highest sustained heat focus on persistence rather than a single spike. The undisputed location for the highest annual mean temperature on Earth is the mining settlement of Dallol, Ethiopia. Historical weather records from 1960 to 1966 documented an average annual temperature of 34.4°C (94.0°F). This extraordinary figure results from the heat remaining consistently high throughout the day and night, year-round, without significant seasonal variation.
Another region known for intense, sustained heat is the Lut Desert, or Dasht-e Lut, in Iran. This desert holds the record for the highest measured land surface temperature (LST). Satellite data has recorded ground temperatures here exceeding 70.7°C (159.3°F), though this measures surface heating, not air temperature.
Climatological Drivers of Extreme Heat
The geography of these extreme regions creates a confluence of atmospheric effects that act as a natural heat-trapping mechanism. A primary driver is the rain shadow effect, where mountain ranges block moisture-laden air from reaching the interior lowlands. As air masses are forced to rise over high mountains, such as the Sierra Nevada west of Death Valley, they cool and release moisture as precipitation on the windward slopes.
Once the dry air passes the mountain crests and descends into the deep valleys, it is subjected to adiabatic warming, also known as compressional heating. As air sinks, increasing atmospheric pressure causes air molecules to collide more frequently, raising the temperature by approximately 10°C for every 1,000 meters (5.5°F per 1,000 feet) of descent. This process creates a superheated, arid air mass that settles in the low-lying basins.
The low elevation of places like Death Valley, which sits 86 meters (282 feet) below sea level, intensifies this heating. The valley’s steep walls trap the air, preventing it from rising and escaping. Furthermore, the lack of vegetation and moisture means solar energy directly heats the dark rock and soil, which then radiates the heat back into the trapped air. This combination of topographic heat trapping and compressional warming produces the most extreme temperatures on Earth.