Short answer
Aridity is lasting dryness characteristic of a climate. Drought is an unusual shortage of water over time relative to what is normal for a place. A desert can be arid without being in drought; it can also have a drought if it becomes drier than its own baseline. 1 2
Aridity describes the usual climate; drought is a departure from the usual water balance.
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| Question | Drought | Aridity |
|---|---|---|
| Timescale | Temporary or episodic | Persistent climate feature |
| Reference | Compared with local normal | Part of local normal |
| Possible together? | Yes | Yes |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Drought. An abnormal period of water deficit relative to expected conditions, often involving precipitation and available water. 1
Aridity. A persistent climatic condition in which low water availability is characteristic of a region. 2
Key differences
NOAA describes drought as prolonged imbalance between water supply and loss, and contrasts it with aridity as a normal dry-climate property. A single dry day is not usually a drought; impacts and duration matter. 1 2
How to tell them apart
Compare conditions with the region’s historical baseline and available water. A low annual rainfall total alone cannot establish drought without context. Different drought indicators track meteorological, agricultural and hydrological effects. 1 2
Where they overlap
Both can mean too little water for a particular use. Arid regions can experience drought, and human water demand can worsen a shortage. 1 2
Edge cases
Definitions of drought vary by sector and location. Water management, soil moisture and evaporation can matter as much as raw rainfall. A permanently dry area is not permanently in drought by definition. 1 2
Why the distinction exists
The distinction separates a climate characteristic from an exceptional event, allowing warnings and resource planning to use the right baseline. 1 2
Common misconceptions
Drought does not mean only “very little rain.” What counts as unusually dry differs between a desert and a normally wet region. 1 2
Examples
A desert with its typical sparse rainfall is arid. If its water balance drops well below its normal pattern for months, it may also be in drought. 1 2
Sources
Sources checked October 3, 2026.
- NOAA Physical Sciences Laboratory — Drought. Drought definition.
- NOAA/NWS — Drought Public Fact Sheet. What is Drought?.