Definition
In a METAR, PY is the weather code used to report spray — small water droplets blown into the air from the surface of a body of water by strong wind. It is reported as a present weather phenomenon when it reduces visibility or is otherwise operationally significant.
Plain English
Wind has lifted water droplets off the surface of the sea or another body of water and blown them into the air. The METAR uses the code PY to say this is happening at the airport.
Context Anchor
Seen in the weather section of a METAR, especially for airports near coastlines, large lakes, or other open water.
Derivation
The two-letter METAR codes are standardized international shorthand. PY does not match the English letters of 'spray' directly; it is simply the assigned code in the global METAR system, chosen to avoid conflict with other two-letter weather codes.
Why Pilots Care
Spray indicates strong surface winds and can reduce visibility near the surface. It is a cue to expect gusty conditions, possible crosswinds, and degraded visual references on approach or takeoff at coastal fields.
Grounding Statement
Picture strong wind tearing mist off waves and pushing it across the airport surface.
Intuition Check
Spray here does not mean someone is spraying a chemical or liquid from equipment. In a METAR, it means wind-blown water droplets from a nearby water surface.
Example Sentence 1
The METAR for the coastal airport included PY in the present weather group, alerting the pilot to strong onshore winds lifting water off the bay.
Example Sentence 2
With PY reported, the crew delayed the low approach until conditions improved.