Weather Reports on Your OFP
Your OFP includes current weather observations (METARs) and forecasts (TAFs) for your departure, destination, and alternate airports. These are in the standard ICAO aviation weather format.
METAR (Current Observation)
A METAR is a snapshot of current weather conditions at an airport. Example:
METAR EHAM 080900Z 24012KT 9999 FEW040 SCT100 12/06 Q1023 NOSIG
Decoded:
| Element | Meaning |
|---|---|
EHAM | Airport ICAO code (Amsterdam Schiphol) |
080900Z | Day 08, 09:00 UTC |
24012KT | Wind from 240 degrees at 12 knots |
9999 | Visibility 10 km or more (essentially unlimited) |
FEW040 | Few clouds at 4,000 ft |
SCT100 | Scattered clouds at 10,000 ft |
12/06 | Temperature 12°C, dewpoint 6°C |
Q1023 | QNH (altimeter setting) 1023 hPa |
NOSIG | No significant changes expected |
Cloud Cover Codes
| SKC / CLR | Sky clear (no clouds) |
| FEW | Few clouds (1-2 oktas, 1/8 to 2/8 of sky covered) |
| SCT | Scattered (3-4 oktas) |
| BKN | Broken (5-7 oktas — mostly cloudy) |
| OVC | Overcast (8 oktas — full cloud cover) |
Common Weather Phenomena
RA | Rain | SN | Snow |
DZ | Drizzle | FG | Fog (visibility below 1000m) |
BR | Mist (visibility 1000-5000m) | HZ | Haze |
TS | Thunderstorm | SH | Showers |
+ | Heavy (e.g., +RA = heavy rain) | - | Light (e.g., -SN = light snow) |
Wind Notation
24012KT— Wind from 240° at 12 knots24012G25KT— Same, gusting to 25 knotsVRB03KT— Variable direction at 3 knots (light and variable)00000KT— Calm (no wind)
TAF (Forecast)
A TAF provides a weather forecast for the next 24-30 hours. It uses the same codes as a METAR but includes change indicators:
| BECMG | Becoming — a gradual change to new conditions |
| TEMPO | Temporary — brief fluctuations (lasting less than an hour at a time) |
| FM | From — an abrupt change to new conditions at the specified time |
| PROB30/PROB40 | Probability of occurrence (30% or 40%) |
Why Weather Matters for Your Flight
- Departure weather — Determines available runways, potential delays, and takeoff performance
- En-route weather — Turbulence, icing levels, and jet stream position affect fuel burn and ride quality
- Destination weather — Determines approach type (visual vs instrument), potential go-arounds, and whether you may need to divert to your alternate
- Alternate weather — Must meet minimum requirements — if the alternate also has bad weather, a more distant alternate may be needed (extra fuel!)