Iraq, situated in Southwest Asia, possesses a climate that is predominantly classified as hot desert. Its geographical location places it within a transition zone, resulting in a climate defined by extremes. The majority of Iraq experiences intense heat and minimal precipitation annually. This environment is characterized by high solar radiation and significant differences between daytime and nighttime temperatures.
Defining the Arid and Semi-Arid Climate
The climate of Iraq is largely governed by the subtropical high-pressure system, which leads to sinking air and widespread suppression of rainfall. According to the Köppen-Geiger classification system, over three-quarters of Iraq falls under either the hot desert climate (BWh) or the hot semi-arid climate (BSh) categories.
The hot desert classification (BWh) covers the expansive central and southern plains. This climate is defined by extremely low annual precipitation and an average annual temperature exceeding 18°C. The semi-arid climate (BSh) is a transitional zone, often found in northern areas. It receives slightly more rainfall than the true desert but is still characterized by high temperatures and limited moisture.
These classifications mean that the bulk of the country maintains very low humidity levels, a characteristic of continental desert environments. While the BWh regions are relentlessly dry, the BSh areas receive just enough precipitation to support sparse steppe vegetation. The persistent presence of the subtropical high dictates that clear skies and intense sunlight are the norm throughout the year.
Significant Regional Variations
Despite the overall arid nature, Iraq’s diverse topography creates distinct regional climate variations. The north and northeast, including the rugged Zagros Mountains of Iraqi Kurdistan, experience a notably different climate. This mountainous zone is influenced by a hot-summer Mediterranean climate (Csa).
These high-altitude areas receive significantly greater precipitation, ranging between 400 and 1,000 millimeters annually. This rainfall is concentrated during the winter, often falling as heavy snow, which is a major source of water for the Tigris and Euphrates rivers. Temperatures are comparatively cooler, with winter minimums frequently dipping below freezing.
Moving south into the central and southern alluvial plains, the climate transitions back to the hot desert (BWh) environment. Cities like Baghdad and Basra experience desert heat and extremely low rainfall, often less than 200 millimeters annually. The far southern coastal areas near the Persian Gulf introduce higher levels of humidity, making the extreme summer temperatures feel more oppressive.
Seasonal Temperature and Precipitation Patterns
The annual climate cycle in Iraq is sharply divided into two principal seasons: a long summer and a short, mild to cool winter. The summer season extends for five to six months, typically beginning in May and lasting through October. During this period, the central and southern regions face relentless heat, with average daily high temperatures regularly exceeding 46°C (115°F).
Cities in the south, such as Basra, frequently record peak summer temperatures reaching as high as 52°C (125°F). This season is characterized by near-total drought, with no precipitation received from June through September. Intense solar heating and lack of cloud cover contribute to the severity and duration of the heat.
The winter season runs roughly from December to February. Days are generally mild, with average highs in Baghdad around 16°C (61°F), but nights can become quite cold. Minimum temperatures in the central plains often drop close to 4°C, and frost is a possibility during cold spells.
Winter is the primary wet season, with approximately 70% of the annual rainfall occurring between November and March. In the mountainous north, winter lows can plummet to severe levels, sometimes reaching -22°C, accompanied by significant snowfall. This precipitation is crucial for agriculture and water reserves, though overall totals remain low outside the northern mountains.
Extreme Meteorological Phenomena
A defining characteristic of Iraq’s climate is the Shamal wind. The Shamal is a strong, dry, northwesterly wind that blows across the country, particularly during the summer months of June and July. These winds are powerful drivers of massive dust and sandstorms that frequently blanket large sections of Iraq.
Iraq is often cited as one of the countries most affected by these events, which can drastically reduce visibility and pose significant health and logistical challenges. The storms typically last between three and five days, picking up fine desert sediment from the alluvial plains. The frequency and severity of these dust events have been increasing, contributing to the harshness of the environment. The climate is also experiencing a trend of more frequent and intense heat waves.