Plain English Meaning

VV in a weather report means the sky is so obscured that there is no normal cloud base to measure. Instead, the report tells you how far up you could see if you were looking straight up from the ground.

Full Definition

In a METAR, VV indicates an indefinite ceiling, meaning the sky is obscured (by fog, heavy precipitation, or similar) and the cloud base cannot be determined. The digits that follow VV give the vertical visibility into the obscuration in hundreds of feet above ground level. For example, VV004 means vertical visibility is 400 feet AGL.

Context Anchor

Seen in METAR aviation weather reports, especially during fog, heavy snow, , or other that hide the sky.