The question of which city is the hottest in the world is not easily answered with a single name, as the definition of “hottest” is ambiguous. Determining the hottest location depends entirely on the specific metric used to measure temperature, ranging from a single, momentary peak to a sustained annual average. The search for the world’s hottest city highlights the global phenomenon of extreme heat, which increasingly affects populated areas across diverse climates, from arid deserts to humid tropical coastlines. Understanding the different ways heat is quantified is necessary before any city can be definitively named a record holder.
How We Measure the Hottest City
Scientists use several distinct metrics to qualify a location as the hottest, moving beyond simple daily air temperature readings.
The Absolute Maximum Temperature measures the single highest air temperature ever recorded at a location, typically taken 1.5 meters above the ground, shielded from direct sunlight. This metric often identifies places with extreme but brief heat events.
Another key measurement is the Highest Average Annual Temperature, which reflects sustained, year-round heat by calculating the mean temperature over a period of 30 years. This shows chronic heat exposure rather than a single peak event. A third, more localized metric is the Highest Average Daily Maximum Temperature, focusing specifically on the average daytime high temperatures during the hottest season, such as the summer months.
The heat index and wet bulb globe temperature (WBGT) are also important, as they incorporate humidity and solar radiation to indicate how the heat feels to a person. These thermal comfort indices provide a more accurate assessment of the physical heat stress on human inhabitants than air temperature alone. For the purpose of identifying the world’s hottest inhabited places, a combination of absolute records and sustained averages provides the most complete picture.
The Cities That Hold the Record
The location with the highest official air temperature ever recorded is Furnace Creek in Death Valley, California, which registered 56.7°C (134°F) on July 10, 1913. While Death Valley is a valley and not a major city, the nearby Furnace Creek Visitor Center remains a permanent settlement and is the standard for this absolute record.
For a more recent and highly scrutinized peak, a temperature of 54.4°C (129.9°F) was recorded there in August 2020.
When focusing on major, densely populated cities that have recorded extreme single-day peaks, the Middle East features prominently. Basra, Iraq, and Kuwait City, Kuwait, have both logged temperatures of 54°C (129.2°F), with Kuwait’s reading occurring in 2016. Ahvaz, Iran, a city of over a million people, also reached 54°C in June 2017, showcasing the intense, single-event heat experienced in the Persian Gulf region.
For sustained, year-round heat, the title shifts to other regions. Dallol, Ethiopia, an abandoned mining settlement, holds the record for the highest average annual temperature at 34.4°C (94.0°F), recorded between 1960 and 1966. However, among currently populated major cities, Mecca (Makkah), Saudi Arabia, is often cited for its high average annual temperature, which reaches approximately 30.7°C (87.3°F). Bangkok, Thailand, also contends for the title of the world’s most consistently hot city, with high temperatures sustained year-round due to its tropical location near the equator.
The city of Quriyat, Oman, holds a distinct and telling record for sustained heat: the highest-ever minimum (night-time) temperature. On June 26, 2018, the mercury never dropped below 42.6°C (108.7°F), indicating that the heat load on its inhabitants is relentless, even after the sun sets. This lack of nocturnal cooling is a particularly dangerous characteristic of extreme urban heat.
Geographic and Meteorological Drivers of Extreme Heat
The intense heat experienced by these record-holding cities is driven by a convergence of local geography and large-scale atmospheric patterns. Many of the hottest places, such as those in the Middle East and the American Southwest, are located in low-latitude regions near large desert masses. Deserts are characterized by a lack of moisture and vegetation, which prevents the sun’s energy from being used for cooling evaporation, instead channeling it into sensible heat that warms the air directly.
A landlocked position, far from the moderating influence of an ocean, allows temperatures to soar without maritime breezes to provide relief. This isolation exacerbates the heating, particularly when combined with low elevation, such as in Death Valley, which sits below sea level. The air descending into these low basins undergoes adiabatic heating, compressing and warming as it sinks.
Within the cities themselves, the Urban Heat Island (UHI) effect is a significant meteorological factor that amplifies temperatures. Urban materials like concrete, asphalt, and dark rooftops absorb and store solar radiation during the day, releasing that heat slowly throughout the night. This heat retention limits the drop in temperature after sunset, resulting in the dangerously high minimum temperatures seen in places like Oman.
Furthermore, stable high-pressure systems often settle over these regions during the summer, which suppresses air movement and prevents the mixing of cooler air from above. This stagnant air traps heat and pollutants near the surface, leading to prolonged heatwaves. The sheer density of buildings and human activity also contributes anthropogenic heat from car engines, air conditioners, and industrial processes, adding a final layer of localized warming to the already extreme meteorological conditions.