Understanding aviation weather reports is a fundamental skill every pilot must master. METAR and TAF are the two most critical weather products you'll use daily—from pre-flight planning to in-flight decisions.
This guide breaks down every element of these reports with real Indian airport examples, making DGCA exam preparation straightforward and practical.
What is METAR & TAF?
METAR (Meteorological Aerodrome Report)
METAR is a real-time weather observation taken at an aerodrome. It tells you what the weather is right now.
Key characteristics:
- Issued every 30 minutes (or hourly at some stations)
- Valid at the time of observation only
- Covers conditions within 8-10 km of the aerodrome
SPECI (Special Report)
A SPECI is an unscheduled METAR issued when significant weather changes occur between regular observations.
Triggers for SPECI:
- Visibility drops below or rises above minima
- Ceiling changes significantly
- Onset or cessation of thunderstorms, freezing precipitation
- Wind shift exceeding 45°
TAF (Terminal Aerodrome Forecast)
TAF is a weather forecast for the aerodrome and its vicinity.
Key characteristics:
- Valid for 24-30 hours
- Covers area within 8 km radius of aerodrome
- Issued 4 times daily (0000, 0600, 1200, 1800 UTC)
METAR Format Breakdown
A METAR follows this standard sequence:
TYPE ICAO DATE/TIME WIND VISIBILITY WEATHER CLOUDS TEMP/DEW QNH REMARKS
Example METAR
METAR VIDP 061030Z 27012KT 4000 HZ SCT020 BKN100 32/18 Q1008 NOSIG
Let's decode each element:
| Element | Value | Meaning | |---------|-------|---------|------| | TYPE | METAR | Routine observation | | ICAO | VIDP | Delhi Airport | | DATE/TIME | 061030Z | 6th day, 10:30 UTC | | WIND | 27012KT | 270° at 12 knots | | VISIBILITY | 4000 | 4000 meters | | WEATHER | HZ | Haze | | CLOUDS | SCT020 BKN100 | Scattered at 2000ft, Broken at 10000ft | | TEMP/DEW | 32/18 | Temp 32°C, Dewpoint 18°C | | QNH | Q1008 | Altimeter 1008 hPa | | TREND | NOSIG | No significant change expected |
Station Identifier (ICAO Code)
Indian airports use 4-letter ICAO codes starting with:
- VA - Western India (Mumbai region)
- VE - Eastern India (Kolkata region)
- VI - Northern India (Delhi region)
- VO - Southern India (Chennai region)
- VV - Reserved
Common Indian Airport Codes
| Code | Airport | |------|---------|-----| | VIDP | Delhi (Indira Gandhi) | | VABB | Mumbai (Chhatrapati Shivaji) | | VOBL | Bengaluru (Kempegowda) | | VOMM | Chennai (Meenambakkam) | | VECC | Kolkata (Netaji Subhas) | | VOHS | Hyderabad (Rajiv Gandhi) | | VAGO | Goa (Dabolim) | | VAJJ | Jaipur | | VIAR | Amritsar | | VOCL | Kozhikode (Calicut) |
Date and Time Group
Format: DDHHMMz
- DD - Day of month (01-31)
- HHMM - Time in hours and minutes
- Z - Zulu time (UTC)
Example: 251430Z = 25th day at 14:30 UTC
To convert to IST: Add 5 hours 30 minutes
- 1430Z = 2000 IST
Wind Group
Format: dddffGff KT or dddffGff MPS
- ddd - Direction in degrees (true north)
- ff - Speed
- G - Gust indicator
- ff - Gust speed
- KT - Knots / MPS - Meters per second
Wind Examples
| Code | Meaning | |------|---------|-----| | 27015KT | 270° at 15 knots | | 36020G35KT | 360° at 20 knots, gusting 35 | | VRB03KT | Variable at 3 knots | | 00000KT | Calm | | 18010KT 150V210 | 180° at 10kt, varying 150°-210° |
Variable Wind Direction: Reported when direction varies by 60° or more and speed exceeds 3 knots.
Visibility
Reported in meters (4 digits) or statute miles (SM).
| Code | Meaning | |------|---------|-----| | 9999 | 10 km or more | | 5000 | 5000 meters | | 0800 | 800 meters | | 0200 | 200 meters | | 0050 | 50 meters | | CAVOK | Ceiling And Visibility OK |
CAVOK Conditions
CAVOK is reported when ALL of the following exist:
- Visibility 10 km or more
- No cloud below 5000 ft or below highest MSA
- No CB or TCU
- No significant weather
Runway Visual Range (RVR)
Format: Rnn/nnnnV or Rnn/nnnn
Example: R28/0600 = Runway 28, RVR 600 meters
| Prefix | Meaning | |--------|---------|-----| | M | Less than (M0200 = below 200m) | | P | More than (P2000 = above 2000m) | | U | Increasing | | D | Decreasing | | N | No change |
Weather Phenomena
Weather is coded using intensity + descriptor + phenomenon.
Intensity Prefixes
| Prefix | Meaning | |--------|---------|-----| | - | Light | | (none) | Moderate | | + | Heavy | | VC | In vicinity (8-16 km) |
Descriptors
| Code | Meaning | |------|---------|-----| | MI | Shallow | | PR | Partial | | BC | Patches | | DR | Drifting | | BL | Blowing | | SH | Showers | | TS | Thunderstorm | | FZ | Freezing |
Precipitation
| Code | Meaning | |------|---------|-----| | RA | Rain | | DZ | Drizzle | | SN | Snow | | SG | Snow grains | | IC | Ice crystals | | PL | Ice pellets | | GR | Hail (>5mm) | | GS | Small hail (<5mm) | | UP | Unknown precipitation |
Obscuration
| Code | Meaning | |------|---------|-----| | FG | Fog (visibility <1000m) | | BR | Mist (visibility 1000-5000m) | | HZ | Haze | | FU | Smoke | | VA | Volcanic ash | | DU | Dust | | SA | Sand |
Other Phenomena
| Code | Meaning | |------|---------|-----| | PO | Dust/sand whirls | | SQ | Squall | | FC | Funnel cloud/tornado | | SS | Sandstorm | | DS | Duststorm |
Weather Examples
| Code | Meaning | |------|---------|-----| | -RA | Light rain | | +TSRA | Heavy thunderstorm with rain | | VCSH | Showers in vicinity | | -FZRA | Light freezing rain | | +TSRAGR | Heavy TS with rain and hail | | BCFG | Fog patches | | MIFG | Shallow fog | | BLDU | Blowing dust |
Cloud Groups
Format: NNNhhh or NNNhhhCB/TCU
- NNN - Amount (FEW, SCT, BKN, OVC)
- hhh - Height in hundreds of feet AGL
- CB/TCU - Cloud type (if significant)
Cloud Amount
| Code | Oktas | Coverage |
|---|---|---|
| FEW | 1-2 | Few (up to 25%) |
| SCT | 3-4 | Scattered (25-50%) |
| BKN | 5-7 | Broken (50-87%) |
| OVC | 8 | Overcast (100%) |
Cloud Height
Height is in hundreds of feet AGL.
| Code | Height AGL |
|---|---|
| 005 | 500 ft |
| 020 | 2000 ft |
| 100 | 10,000 ft |
| 250 | 25,000 ft |
Significant Cloud Types
| Code | Type | Significance | |------|------|--------------|-----| | CB | Cumulonimbus | Thunderstorm cloud | | TCU | Towering Cumulus | Developing CB |
Cloud Examples
| Code | Meaning | |------|---------|-----| | FEW010 | Few clouds at 1000 ft | | SCT025 | Scattered at 2500 ft | | BKN040CB | Broken CB at 4000 ft | | OVC002 | Overcast at 200 ft | | NSC | No significant cloud | | NCD | No cloud detected (auto) | | SKC | Sky clear |
Vertical Visibility
When sky obscured: VVhhh
Example: VV003 = Vertical visibility 300 ft (sky obscured)
Temperature and Dewpoint
Format: TT/DD (in whole degrees Celsius)
- Negative values prefixed with M (minus)
| Code | Meaning | |------|---------|-----| | 28/21 | Temp 28°C, Dewpoint 21°C | | 05/M02 | Temp 5°C, Dewpoint -2°C | | M08/M12 | Temp -8°C, Dewpoint -12°C |
Relative Humidity Tip: When temp equals dewpoint, RH ≈ 100% (fog likely).
Altimeter Setting (QNH)
Format: Qnnnn (hPa) or Annnn (inches Hg)
| Code | Meaning | |------|---------|-----| | Q1013 | QNH 1013 hPa | | Q0996 | QNH 996 hPa | | A2992 | Altimeter 29.92 inHg |
Standard Pressure: Q1013 or A2992
Trend Forecast (METAR only)
Added at end of METAR to indicate expected changes in next 2 hours.
| Code | Meaning | |------|---------|-----| | NOSIG | No significant change | | BECMG | Becoming (gradual change) | | TEMPO | Temporary fluctuations |
Example: TEMPO 3000 TSRA = Temporarily visibility 3000m with thunderstorm rain
TAF Format
TAF follows similar format but includes validity period and change indicators.
TAF VIDP 060500Z 0606/0712 31010KT 6000 HZ SCT030
TEMPO 0608/0612 4000 TSRA BKN025CB
BECMG 0612/0614 27008KT 8000 NSW SCT035
TAF Elements
| Element | Example | Meaning | |---------|---------|---------|-----| | Validity | 0606/0712 | From 6th 0600Z to 7th 1200Z | | Initial conditions | 31010KT 6000 HZ | Base forecast | | TEMPO | 0608/0612 | Temporary: 0600-1200Z on 6th | | BECMG | 0612/0614 | Becoming: during 1200-1400Z |
TAF Change Indicators
| Code | Meaning | Duration |
|---|---|---|
| BECMG | Becoming | Change occurs during period |
| TEMPO | Temporary | <1 hour each, <50% of period |
| FM | From | Permanent change from time |
| PROB30 | 30% probability | Low likelihood |
| PROB40 | 40% probability | Moderate likelihood |
NSW (No Significant Weather)
Used in BECMG/TEMPO to indicate weather has ended.
Example: BECMG 1214/1216 NSW = Weather clearing between 1200-1600Z
Decoding Practice: Indian Airport METARs
Example 1: Delhi (VIDP)
METAR VIDP 150830Z 27008KT 2000 HZ SCT020 BKN100 34/19 Q1006 NOSIG
Decode:
- Delhi, 15th at 0830Z (1400 IST)
- Wind 270° at 8 knots
- Visibility 2000m in haze
- Scattered cloud at 2000ft, broken at 10000ft
- Temperature 34°C, dewpoint 19°C
- QNH 1006 hPa
- No significant change expected
Example 2: Mumbai (VABB)
METAR VABB 150900Z 29015G25KT 5000 TSRA SCT018CB BKN025 OVC080 27/24 Q1008 TEMPO 2000 +TSRA
Decode:
- Mumbai, 15th at 0900Z
- Wind 290° at 15kt gusting 25kt
- Visibility 5000m, thunderstorm with rain
- Scattered CB at 1800ft, broken at 2500ft, overcast at 8000ft
- Temp 27°C, dewpoint 24°C (high humidity)
- QNH 1008 hPa
- Temporarily expect 2000m visibility with heavy TS rain
Example 3: Bengaluru (VOBL)
METAR VOBL 150830Z 09005KT CAVOK 28/16 Q1012 NOSIG
Decode:
- Bengaluru, 15th at 0830Z
- Wind 090° at 5 knots
- CAVOK (vis >10km, no significant cloud, no weather)
- Temp 28°C, dewpoint 16°C
- QNH 1012 hPa
- No significant change
Example 4: Kolkata (VECC) - Poor Visibility
METAR VECC 150300Z 00000KT 0400 FG VV001 18/18 Q1014 BECMG 0800 BR
Decode:
- Kolkata, 15th at 0300Z
- Calm wind
- Visibility 400m in fog
- Vertical visibility 100ft (sky obscured)
- Temp = Dewpoint = 18°C (saturated air)
- QNH 1014 hPa
- Becoming 800m visibility in mist
Example 5: Chennai (VOMM) - TAF
TAF VOMM 150500Z 1506/1612 18012KT 6000 HZ FEW025 SCT100
TEMPO 1509/1514 4000 TSRA SCT020CB BKN040
BECMG 1514/1516 24008KT 8000 NSW SCT030
PROB30 1602/1606 3000 BR
Decode:
- Chennai TAF issued 15th at 0500Z
- Valid 15th 0600Z to 16th 1200Z
- Base: 180° at 12kt, 6km haze, few at 2500ft
- Temporary (0900-1400Z): 4km, TS rain, scattered CB
- Becoming (1400-1600Z): 240° at 8kt, 8km, weather ending
- 30% probability (0200-0600Z on 16th): 3km mist
Quick Reference Tables
Weather Codes Summary
| Category | Codes |
|---|---|
| Precipitation | RA DZ SN SG IC PL GR GS |
| Obscuration | FG BR HZ FU DU SA VA |
| Descriptors | TS SH FZ BC MI PR DR BL |
| Other | PO SQ FC SS DS |
Cloud Abbreviations
| Code | Meaning | Oktas |
|---|---|---|
| SKC/CLR | Clear | 0 |
| FEW | Few | 1-2 |
| SCT | Scattered | 3-4 |
| BKN | Broken | 5-7 |
| OVC | Overcast | 8 |
Visibility Conversions
| Meters | Statute Miles | Condition | |--------|---------------|-----------|-----| | <1000 | <5/8 SM | Fog | | 1000-5000 | 5/8-3 SM | Mist/Haze | | 5000-9999 | 3-6 SM | Moderate | | 9999+ | 6+ SM | Good |
Common DGCA Exam Questions
Q1: What does CAVOK mean? A: Visibility ≥10km, no cloud below 5000ft or MSA, no CB/TCU, no significant weather.
Q2: Difference between FG and BR? A: FG (fog) = visibility <1000m; BR (mist) = visibility 1000-5000m. Both caused by water droplets.
Q3: What triggers a SPECI? A: Significant changes in visibility, ceiling, wind, or onset/end of important weather phenomena.
Q4: How to identify thunderstorm in METAR? A: Look for TS in weather group and/or CB in cloud group.
Q5: TEMPO vs BECMG? A: TEMPO = temporary fluctuations (<1hr, <50% of time). BECMG = permanent change occurring during specified period.
Exam Tips
-
Memorize codes systematically - Group by category (precipitation, obscuration, etc.)
-
Practice with real METARs - Check aviationweather.gov or Indian airport METAR sites daily
-
Time conversions - Always convert Z to IST by adding 5:30
-
Cloud height - Remember it's in hundreds of feet AGL, not MSL
-
CAVOK conditions - Know all three requirements
-
Intensity matters - Light (-), Moderate (no prefix), Heavy (+)
-
Vicinity (VC) - Weather is 8-16 km away, not at the airport
Conclusion
METAR and TAF decoding becomes intuitive with practice. Start by reading actual reports from Indian airports daily—this builds familiarity with common patterns and codes.
For DGCA exams, focus on:
- Knowing all weather codes and their meanings
- Understanding TAF change indicators
- Converting between units (Z to IST, meters to SM)
- Recognizing hazardous weather indicators (CB, TS, FZ)
Bookmark this guide and practice with real weather reports. Within a few weeks, decoding will become second nature.
