Definition
St is the standard meteorological abbreviation for stratus, a low-level cloud type that forms in flat, featureless, horizontal layers or sheets, typically with a uniform gray base and little vertical development.
Plain English
St is shorthand for stratus — the flat, gray, layered cloud that often covers the sky like a low ceiling and can produce mist, drizzle, or poor visibility.
Context Anchor
Seen in weather and cloud-type discussions, especially when learning to identify cloud forms and the flying conditions they may bring.
Derivation
From the Latin stratus, meaning ‘spread out’ or ‘laid down flat’ — the same root as ‘stratum’ (a layer). The name fits the cloud’s appearance: a layer spread flat across the sky, rather than piled up like a cumulus.
Why Pilots Care
Low stratus layers create reduced ceilings and visibility that can force instrument procedures or delay departures.
Intuition Check
Do not read St as “street” or “saint” in this weather context. In aviation cloud notation, St means stratus.
Example Sentence 1
The area forecast called for St below 1,000 feet along the coast, so the pilot delayed departure until the layer lifted.
Example Sentence 2
Scattered St layers were forecast to lift by mid-morning, allowing VFR departure after 10 a.m.