Drizzle

Drizzle is a form of liquid precipitation consisting of very small droplets, typically 0.2 to 0.5 millimeters in diameter, with a light fall rate usually less than 1 millimeter per hour. The droplets are finer than rain, and drizzle often produces a fine, misty layer on surfaces. Visibility is commonly reduced, but not as severely as during heavier rain.

Drizzle forms in shallow, stratified clouds such as stratus and stratocumulus, and is often associated with fog or high humidity near the surface. Droplets grow slowly through condensation and limited coalescence, so they remain small and do not develop into larger rain droplets. Some drizzle also results when small rain droplets evaporate as they descend through drier air, leaving behind tiny droplets.

In weather reporting, drizzle is coded as DZ and can be described as light, moderate, or heavy. It is more frequent in maritime and coastal climates and in cool, stable air masses near the ground. Drizzle can persist for long periods, producing damp conditions without heavy accumulation.

The practical effects of drizzle are modest: surfaces become damp, pavement does not typically flood, and mist-like visibility can affect aviation and road travel. It is distinct from mist or fog because drizzle consists of actual precipitation, with droplets that are tiny but larger than those typically found in mist or fog.