ASPM: Local Weather Codes

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METAR records include codes describing weather phenomena observed at or near the airport. The ASPM team, in collaboration with the FAA Weather Office, developed a scoring system for rating the severity of the airport weather.

Each weather phenomenon is given a score of 1–3 (Minor, Moderate, or Severe), which can be adjusted up or down for intensity or descriptors (such as “Heavy”, “Patchy”, or “In the Vicinity”) to a maximum score of 3 or a minimum of 1. Records with no weather phenomena reported receive an airport weather score of “0” (none). Any record with a thunderstorm is scored as Severe, even if it is only in the vicinity.

If several weather phenomena are reported for the same record, then the most severe determines the score. For example, for the weather RA FG (Rain with Fog), rain would be scored as a 2, and Fog as a 3. The highest score dominates, so the airport weather is scored as a 3 (Severe).

In the table below, the scores for each phenomenon are listed, followed by the adjustments (ranging from +1 to -2) for intensity and descriptors.

Code Description Severity Score
DZ Drizzle 1
UP Unknown Precipitation* 1
HZ Haze 1
PY Spray 1
RA Rain 2
BR Mist 2
FU Smoke 2
DU Dust 2
SA Sand 2
SH Showers 2
SN Snow 3
SG Snow Grains 3
IC Ice Crystals 3
PL Ice Pellets 3
GR Hail 3
GS Small Hail or Snow Pellets 3
FG Fog 3
VA Volcanic Hash 3
PO Dust/Sand Whirls 3
SQ Squalls 3
FC Funnel Cloud 3
+FC Tornado or Waterspout 3
SS Sandstorm 3
DS Duststorm 3
TS Thunderstorm 3
FZ Freezing 3
MI Shallow -1
PR Partial -1
BC Patches -2
VC In the Vicinity -2
DR Low Drifting +1
BL Blowing +1
+ Heavy +1
- Light No change