Fog is composed of very small water droplets and sometimes minute ice particles in suspension in the atmosphere, reducing the horizontal visibility at the Earth`s surface to less than 1000 meters. Fog has a significant impact on the conduct of flying operations, particularly landing and take-off.

How to Report Fog and different types of Fog in METAR/SPECI?

The letter abbreviation FG shall be used when the obstruction to vision consists of water droplets or ice crystals (fog or ice fog). For w´w´= FG to be reported without the qualifiers MI, BC or VC, the Visibility reported in the group VVVV shall be less than 1000 metres.

Shallow Fog

For w´w´= MIFG to be reported, the Visibility at two metres above ground level shall be 1000 metres or more and the apparent Visibility in the fog layer shall be less than 1000 metres.


Fog in Vicinity

The letter abbreviation VCFG shall be used to report any type of fog observed in the vicinity of the aerodrome.

Fog in Patches

The letter abbreviation BCFG shall be used to report fog patches and the letter abbreviation PRFG to report fog covering part of the aerodrome; the apparent Visibility in the fog patch or bank shall be less than 1000 metres, the fog extending to at least two metres above ground level.

Note: BCFG should be used only when the Visibility in parts of the aerodrome is 1000 metres or more although, when the fog is close to the observing.

  •  The vertical extent of fog ranges from a few meters to several hundred meters.