Drought hits hardest in the subtropical bands that circle the Earth near 30°N and 30°S latitude, where large-scale atmospheric circulation pushes dry air downward year-round. The regions most frequently affected include sub-Saharan Africa (especially the Sahel and Horn of Africa), northeastern Brazil, Australia’s interior, Central Asia, and parts of the Middle East and southwestern North America. These areas share a combination of low baseline rainfall, high temperatures, and climate patterns that periodically shut off what little moisture they normally receive.
Why Certain Latitudes Stay Dry
The global pattern of drought isn’t random. Earth’s atmosphere operates like a conveyor belt: warm, moist air rises near the equator, drops its rain in tropical forests, then moves poleward and sinks back down around 30 degrees north and south. That sinking air suppresses cloud formation and creates the subtropical dry zones where most of the world’s deserts sit. The Sahara, the Arabian Desert, the Sonoran Desert in Mexico and the U.S. Southwest, the Atacama in Chile, and Australia’s interior all fall along these bands.
Climate models project that warming temperatures will push these dry zones farther from the equator over the coming decades. That means regions just outside the traditional desert belts, places like the Mediterranean, southern Australia, and the U.S. southern plains, face increasing drought risk even though they’ve historically received moderate rainfall.
The Sahel and Horn of Africa
No region on Earth has a more devastating modern drought record than the Sahel, the semi-arid belt stretching across Africa just south of the Sahara from Senegal to Sudan. The worst drought of the 20th century struck between 1982 and 1985, affecting more than 90% of the entire region. Millions of people lost crops and livestock, and famine followed in multiple countries.
The Sahel’s rainfall depends heavily on the West African monsoon, which can weaken or shift for years at a time in response to changes in Atlantic Ocean surface temperatures. When the monsoon fails, there’s essentially no backup water source. Since 2005, drought episodes and their intensity have diminished somewhat across the Sahel, but the region remains deeply vulnerable. In the Horn of Africa, countries like Somalia, Ethiopia, and Kenya experienced five consecutive failed rainy seasons between 2020 and 2023, one of the longest such stretches on record.
Southern Africa faces its own pattern. Zimbabwe estimated that 2.7 million people would go hungry in 2024 due to drought conditions that spread across multiple nations in the region. Across the broader area, 45 million children are living through overlapping crises intensified by climate shifts, including drought, floods, malnutrition, and disease outbreaks.
Northeastern Brazil’s Sertão
Brazil’s semi-arid interior, known as the Sertão, is the most drought-prone region in South America. Droughts here are recurrent, with most lasting one to two years, but longer events have caused severe damage throughout the 20th and 21st centuries. Notable multi-year droughts struck in 1930 to 1932, 1941 to 1943, 1951 to 1954 (four years), and 1979 to 1983 (five years).
The Sertão’s rainfall depends on the position of a tropical rainfall band over the Atlantic. When that band shifts northward, as it does during El Niño events, northeastern Brazil dries out. The mid-northern and Sertão sub-regions consistently show the most critical drought severity in trend analyses. Tens of millions of people live in this area, and many rely on rain-fed agriculture or small reservoirs that can empty within months of a missed wet season.
Australia’s Interior and Murray-Darling Basin
Australia is the driest inhabited continent, and drought is a defining feature of its climate. The most significant modern event, the Millennium Drought, lasted from the late 1990s through 2010 across much of the Murray-Darling Basin, the country’s most important agricultural region. That 13-year dry spell was so severe it forced a complete overhaul of how water is managed across the basin, leading to the creation of a national Basin Plan.
Australia’s drought cycles are closely tied to El Niño events in the Pacific Ocean and a separate pattern called the Indian Ocean Dipole. When both align unfavorably, rainfall across eastern and southern Australia can drop well below average for multiple years. The interior receives so little rain to begin with, often under 250 millimeters (about 10 inches) per year, that even a modest decline pushes the landscape into severe drought quickly.
Central Asia’s Expanding Drylands
The steppes and deserts of Central Asia, spanning Kazakhstan, Uzbekistan, Turkmenistan, and surrounding areas, have seen increasing drought pressure over the past two decades. Research covering 2001 to 2020 found that all five major vegetation types in the region (grasslands, croplands, shrublands, forests, and wetlands) responded to worsening drought by crossing stress thresholds at various points during that period. Shrublands showed the largest percentage of area pushed past its drought tolerance.
The causes vary by landscape. For grasslands, shrublands, and wetlands, soil moisture is the primary driver. Croplands depend most on precipitation, while forests are sensitive to the difference between how much moisture the air can hold and how much it actually contains, a gap that widens as temperatures rise. The Aral Sea region, already devastated by decades of water diversion for irrigation, sits at the center of this expanding dry zone.
The Middle East and Southwest Asia
The arc from eastern Syria through Iraq, Iran, and into Afghanistan and Pakistan contains some of the fastest-drying landscapes on the planet. Much of this region receives under 250 millimeters of annual rainfall, and groundwater reserves are being depleted far faster than they recharge. Iran experienced its worst drought in 50 years during 2021, with reservoir levels dropping to critical lows across the country.
Rising temperatures compound the problem. Even when rain does fall, hotter air evaporates soil moisture faster, meaning the same amount of precipitation produces less usable water than it did decades ago. This “hotter drought” phenomenon is increasingly recognized as a multiplier in already-dry regions worldwide.
Southwestern North America
The U.S. Southwest and northern Mexico have been locked in what researchers have called a megadrought since 2000, with soil moisture levels at their lowest point in at least 1,200 years. States like Arizona, New Mexico, Nevada, Utah, and parts of California depend heavily on the Colorado River, which has seen its flow decline by roughly 20% compared to the 20th-century average.
This region sits right along the northern edge of the subtropical dry zone, making it particularly sensitive to the poleward expansion of that zone as the climate warms. Winter snowpack in the Rocky Mountains, which feeds rivers throughout the summer, has been declining. The combination of reduced snowmelt and higher evaporation rates means drought conditions persist even in years with near-normal precipitation.
Small Islands and Pacific Nations
Drought doesn’t only strike large landmasses. Low-lying Pacific island nations like the Marshall Islands are acutely vulnerable because they have almost no groundwater reserves and depend on rainfall collected in tanks. During a 2024 drought event in the Marshall Islands, nearly 14,000 people were affected, and the immediate priority was simply providing enough water for drinking and basic household use. A single dry season that might barely register on a continental scale can become a full-blown water crisis on a small island within weeks.
What Makes Some Regions Recover Faster
The difference between a manageable dry spell and a catastrophic drought often comes down to infrastructure, soil type, and economic buffers. Australia and the U.S. Southwest, while severely drought-prone, have extensive reservoir systems, groundwater access, and the financial resources to truck in water or retire farmland temporarily. The Sahel and Horn of Africa, by contrast, have far less infrastructure and far more people who depend directly on rain-fed agriculture.
Soil also matters. Sandy soils in arid regions lose moisture quickly and recover slowly. Clay-rich soils retain water longer but can crack and become water-repellent after prolonged drying, making the first rains after a drought run off the surface rather than soak in. Regions with degraded soils from overgrazing or deforestation take longer to bounce back, which is why parts of the Sahel and Central Asia experience drought effects that linger well after rainfall returns to normal.