Droughts concentrate in specific belts and regions around the world, driven by atmospheric circulation patterns, ocean temperatures, and geography. The highest-frequency zones include the western United States, the African Sahel, the Horn of Africa, southern Africa, the Mediterranean, South America, eastern Australia, and parts of Russia and Central Asia. Between 2000 and 2020, several of these regions experienced drought events with unprecedented intensity compared to the previous half-century.
The Subtropical Dry Belt
The single biggest factor determining where droughts cluster is a global atmospheric pattern centered around 30 degrees north and south of the equator. Warm, moist air rises near the tropics, producing heavy rainfall. That air then moves toward the poles, losing its moisture along the way, and descends over the subtropics as dry, warming air. This creates semi-permanent high-pressure zones where skies stay clear and rainfall is consistently low.
This mechanism explains why many of the world’s great deserts and drought-prone regions sit in a band across northern Africa (the Sahara and Sahel), the Middle East, the southwestern United States, northern Mexico, and southern Australia. It also explains why the southern tips of Africa and South America are vulnerable. These areas don’t just get less rain on average; they’re also the first to tip into severe drought when rainfall drops even slightly below normal.
Africa: The Most Drought-Affected Continent
Droughts accounted for only 6% of all natural disasters between 1970 and 2019, but caused 34% of all disaster-related deaths, mostly from famine in African countries. The continent has two distinct drought zones that operate on different triggers.
The Sahel, the semi-arid strip south of the Sahara stretching from Senegal to Sudan, experienced one of the most studied droughts of the 20th century. Research from NOAA’s Geophysical Fluid Dynamics Laboratory has shown that Sahel drought is closely tied to ocean temperature differences between the Northern and Southern Hemispheres. When northern ocean waters cool relative to southern waters, tropical rain belts shift southward, pulling moisture away from the Sahel. Industrial air pollution in the Northern Hemisphere likely contributed to mid-century drying by cooling the north, while cleaner air in recent decades has allowed some rainfall recovery.
The Horn of Africa, including Ethiopia, Kenya, and Somalia, faces a different pattern. A triple-dip cycle of cooler-than-normal Pacific Ocean temperatures from 2020 to 2023 produced three consecutive years of drought, the worst in 40 years, leaving 23 million people facing severe hunger.
Western United States and Mexico
The ongoing drought affecting the southwestern United States and Mexico has persisted for more than two decades and is likely the most severe in 1,200 years. An analysis using over 1,500 tree-ring records to reconstruct soil moisture back to 800 CE found that 2000 to 2021 was the driest 22-year period in that entire span. Researchers have classified it as an emerging megadrought, a multidecadal event that exceeds 20th-century droughts like those of the 1930s Dust Bowl and 1950s in both duration and geographic reach.
The region’s vulnerability comes from multiple factors stacking together. It sits at the edge of the subtropical dry belt, and mountain ranges along the Pacific coast create a rain shadow effect. Coastal storms moving east collide with peaks above 10,000 feet, dump their moisture on the western slopes, and leave little for the land on the other side. Rising temperatures have intensified the problem by increasing evaporation from soil and reservoirs, meaning that even average rainfall years now produce drier conditions on the ground.
The Mediterranean and Southern Europe
The Mediterranean basin is one of the most rapidly drying regions on Earth. Climate projections show soil moisture drought duration in the Mediterranean increasing dramatically with warming. At 2°C of global warming, the region is projected to experience roughly 58 drought days per year, a 107% increase over late 20th-century levels. At 3°C, that rises to 71 days (a 154% increase), and at 4°C it reaches 125 days, more than tripling. Southern and eastern Europe, including Spain, Italy, Greece, and Turkey, are already seeing more frequent and intense dry spells compared to the 1950-2000 baseline.
South America, Australia, and Asia
South America’s drought risk centers on Brazil and the southern cone. Northeastern Brazil is especially vulnerable during certain Pacific Ocean cycles, when warmer-than-normal waters in the central Pacific shift rainfall patterns away from the continent. The 1997 cycle contributed to severe forest fires across Brazil and Southeast Asia simultaneously. Southern South America, including parts of Argentina and Chile, faces increasing drought frequency linked to long-term drying trends.
In Australia, the eastern and southern coasts are the primary drought zones. Eastern Australia experienced severe drought conditions in the early 2000s and again around 2019, contributing to catastrophic wildfire seasons. The country’s drought patterns are tightly linked to Pacific Ocean temperature cycles, with cooler Pacific phases typically suppressing rainfall across the eastern half of the continent.
In Asia, drought hotspots include northeastern China, India, and Central Asia. India and the Sahel share a vulnerability to disruptions in monsoon rainfall. When seasonal rains arrive late, arrive weakened, or fail to arrive at all, and above-normal temperatures increase evaporation from the soil, conditions can deteriorate within weeks. These rapid-onset events are sometimes called flash droughts, and their global hotspots include Brazil, the Sahel, the Great Rift Valley, India, the central United States, southwestern Russia, and northeastern China.
How Ocean Cycles Shift Drought Patterns
The same region can swing between wet and dry depending on the phase of large-scale ocean temperature cycles. The most influential is the periodic warming and cooling of the central and eastern Pacific Ocean, which rearranges rainfall patterns across multiple continents at once.
During the warm phase, southern Africa, parts of the Sahel, Indonesia, the Philippines, northeastern China, and Papua New Guinea tend to get drier. The warm phase triggered a 1991-1992 drought across southern Africa that affected nearly 100 million people. During the cool phase, the effects roughly reverse: southern Africa gets wetter, but equatorial East Africa dries out, Central Asia sees reduced rainfall from January through May, and parts of the Pacific coast of South America become drier. The devastating 2020-2023 Horn of Africa drought coincided with three consecutive years of this cool phase.
This means that many regions experience drought not as a permanent condition but as a recurring one, with years or even decades of adequate rainfall interrupted by intense dry periods when ocean conditions shift.
Four Types of Drought
Where drought “occurs” also depends on what kind of drought you’re measuring, because they don’t always overlap geographically. Meteorological drought is simply a rainfall deficit: less rain fell than normal for a sustained period. Hydrological drought shows up in dropping reservoir levels, shrinking rivers, and falling water tables, sometimes months after the rain stopped falling. Agricultural drought is defined by soil moisture: when crops and pastures can’t get enough water to grow, regardless of what reservoir levels look like. Socioeconomic drought occurs when water shortages start affecting the supply of food, energy, or other goods.
A region can experience agricultural drought without hydrological drought if high temperatures dry out topsoil faster than usual, even when deeper water supplies remain adequate. Conversely, a region can have normal rainfall but face hydrological drought if years of prior deficits have drained underground aquifers. This is why drought maps from different agencies sometimes tell different stories about the same area.
Where Droughts Are Getting Worse
Climate projections from the IPCC indicate that even if global warming stabilizes at 1.5°C above pre-industrial levels, the Mediterranean, western and eastern southern Africa, southern Australia, and parts of South America will face more severe agricultural and ecological droughts. At 2°C of warming, the list expands to include western and central Europe, East Asia, Central America, the Caribbean, and most of North America. At 4°C, roughly half of all inhabited regions worldwide would experience increased drought severity.
The combination of rising temperatures and shifting rainfall patterns has already made South America, the western United States, the Horn of Africa, the Mediterranean, eastern Russia, and eastern Australia particularly prone to drought compared to historical baselines. For these regions, drought is no longer an occasional disruption. It is becoming a defining feature of the climate.