Definition
In a METAR, DZ is the precipitation code for drizzle: very small, closely spaced water droplets falling from low stratus clouds or fog. Drops are smaller than rain (less than 0.5 mm in diameter) and appear to float and drift with the air rather than fall straight down.
Plain English
DZ on a weather report means it's drizzling — that fine, misty rain made up of tiny droplets that hang in the air rather than falling like normal rain.
Context Anchor
Seen in METAR weather reports when present weather is coded, such as -DZ for light drizzle or FZDZ for freezing drizzle.
Derivation
From Old English 'dreosan,' meaning 'to fall.' The aviation code DZ is simply the first and last consonants of 'drizzle,' a pattern used throughout METAR codes (RA for rain, SN for snow).
Why Pilots Care
Drizzle reduces visibility and can cause airframe icing when temperatures are near freezing, affecting takeoff, landing, and aircraft handling.
Grounding Statement
Picture walking outside and feeling a steady fine wet spray on your face instead of distinct raindrops.
Intuition Check
Drizzle does not simply mean “light rain” in a METAR. It means very small water drops; light rain is coded separately as -RA.
Example Sentence 1
The METAR reported -DZ with a 400-foot ceiling, so the flight was filed IFR.
Example Sentence 2
Light DZ during the approach made the runway surface slippery without the heavy runoff of rain.