AIM 

4/20/23 

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Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR) (Back) 

Key to Aerodrome Forecast (TAF) and Aviation 

Routine Weather Report (METAR) (Back) 

In 

METAR

, ReMarK indicator & remarks. For example: Sea- Level 

Pressure in hectoPascals & tenths, as shown: 1004.5 hPa; Temp/dew-
point in tenths 

°

C, as shown: temp. 18.2

°

C, dew-point 15.9

°

C 

RMK SLP045 
T01820159 

FM091930 

FroM: changes are expected at: 2-digit date, 2-digit hour, and 2-digit 
minute beginning time: indicates significant change. Each FM starts on a 
new line, indented 5 spaces 

TEMPO 
0920/0922 

TEMPOrary: changes expected for <1 hour and in total, < half of the 
period between the 2-digit date and 2-digit hour beginning, and 2-digit 
date and 2-digit hour ending time 

PROB30 
1004/1007 

PROBability and 2-digit percent (30 or 40): probable condition in the 
period between  the 2-digit date & 2-digit hour beginning time, and the 
2-digit date and 2-digit hour ending time 

BECMG 
1013/1015 

BECoMinG: change expected in the period between the 2-digit date and 
2-digit hour beginning time, and the 2-digit date and 2-digit hour ending 
time 

Table of Significant Present, Forecast and Recent Weather - Grouped in categories and 
used in the order listed below; or as needed in TAF, No Significant Weather. 

Qualifiers 
Intensity or Proximity 
“-”

 = Light 

No sign

 = Moderate 

“+”

 = Heavy 

“VC”

 = Vicinity, but not at aerodrome. In the US METAR, 5 to 10 SM from the point of observation. In the US 

TAF, 5 to 10 SM from the center of the runway complex. Elsewhere, within 8000m. 

Descriptor 
BC

 – Patches 

BL

 – Blowing 

DR

 – Drifting 

FZ

 – Freezing 

MI

 – Shallow 

PR

 – Partial 

SH

 – Showers 

TS

 – Thunderstorm 

Weather Phenomena 
Precipitation 
DZ

 – Drizzle 

GR

 – Hail 

GS

 – Small Hail/Snow Pellets 

IC

 – Ice Crystals 

PL

 – Ice Pellets 

RA

 – Rain 

SG

 – Snow Grains 

SN

 – Snow 

UP

 – Unknown Precipitation in automated observations 

Obscuration 
BR

 – Mist (≥5/8SM) 

DU

 – Widespread Dust 

FG

 – Fog (<5/8SM) 

FU

 – Smoke 

HZ

 – Haze 

PY

 – Spray 

SA

 – Sand 

VA

 – Volcanic Ash 

Other 
DS

 – Dust Storm 

FC

 – Funnel Cloud 

+FC

 – Tornado or Waterspout 

PO

 – Well developed dust or sand whirls 

SQ

 – Squall 

SS

 – Sandstorm 

- Explanations in parentheses “()” indicate different worldwide practices. 
- Ceiling is not specified; defined as the lowest broken or overcast layer, or the vertical visibility. 
- NWS TAFs exclude BECMG groups and temperature forecasts, NWS TAFS do not use PROB in the first 9 
hours of a TAF; NWS METARs exclude trend forecasts. US Military TAFs include Turbulence and Icing groups. 

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Meteorology