Definition
A sky condition reported in a METAR when 8/8 (all eight oktas) of the sky is covered by clouds at a given layer. OVC is the densest of the standard sky cover reports, sitting above FEW (1–2/8), SCT (3–4/8), and BKN (5–7/8). It is followed by a three-digit number giving the height of the cloud base in hundreds of feet above ground level (e.g., OVC050 = overcast layer at 5,000 feet AGL).
Plain English
The sky above the station is completely covered by a layer of cloud, with the base of that layer at the height shown.
Context Anchor
Seen in METAR weather reports, especially in the sky condition part of the report, such as OVC008 or OVC025.
Derivation
From the old English ‘overcast,’ meaning ‘cast over’ or ‘covered over.’ The sky is pictured as something that has been thrown over with cloud, edge to edge.
Why Pilots Care
An overcast layer sets the ceiling height and determines whether visual or instrument flight rules apply for takeoff, en route, and landing.
Intuition Check
Overcast does not just mean “somewhat cloudy.” In a METAR, OVC means the reported cloud layer covers the whole sky from the observer’s point of view.
Example Sentence 1
The METAR reported OVC008, so the ceiling was only 800 feet and the flight had to go IFR.
Example Sentence 2
With an overcast ceiling at 1500 feet, the flight remained in the traffic pattern under visual rules.