A partial METAR decoder with transparent, user-entered weather planning thresholds.
Start here
- Paste the complete METAR you want to examine.
- Enter the wind, visibility and cloud thresholds you want to compare, then choose Calculate.
- Read the decoded groups and threshold results together.
How to read the results
The risk tags compare your entered thresholds. The calculation basis below explains which METAR groups are recognised.
Optional aircraft profile: Manual values
METAR Decoder and UAS Weather Risk Tags
Planning output only. Verify assumptions and results against authoritative data, manufacturer information, approved procedures, test evidence and competent engineering or regulatory review before use.
Calculation basis
The decoder recognises common station/time, wind, visibility, weather, cloud, temperature/dew-point and pressure groups. Wind in metres per second is converted to knots for threshold comparison.
Limitations and verification
- This is a partial decoder and does not implement the complete ICAO/WMO METAR specification or all national variations.
- Risk tags use entered planning thresholds and are not a regulatory go/no-go decision.
- Always use the complete current official weather briefing and competent operational review.
Version and review status
Formula set: v1.2
Staging review date: 17 August 2026
Status: Staging beta pending user acceptance and cross-browser checks.
Using this calculator
A partial METAR decoder with transparent, user-entered weather planning thresholds.
Inputs and units
| Input | Unit or format |
|---|---|
| Raw METAR | METAR text |
| Aircraft wind/gust planning limit | kt |
| Minimum visibility target | m |
| Minimum cloud-base target | ft |
Model and formula
Recognised METAR groups are decoded and compared with the entered wind/gust, visibility and cloud-base thresholds. This is a token decoder and threshold check, not a forecast or a complete weather model.
Worked example
Enter EGLL 031250Z 21014G24KT 8000 -RA BKN018 08/07 Q1012 with a 22 kt wind/gust limit, 5,000 m visibility target and 500 ft cloud-base target. The recognised groups report wind from 210° at 14 kt gusting 24 kt, visibility 8,000 m, weather group -RA, broken cloud at 1,800 ft, temperature/dew point 8/7 °C and QNH 1,012 hPa. The 24 kt gust exceeds the entered wind limit.
Interpreting the result
This is a synthetic worked input, not current weather. The day/time group does not supply month or year. Check the complete current official briefing, report age and representativeness for the operating site. Unrecognised groups and national variations require manual interpretation.
Limits and verification
- This is a partial decoder and does not implement the complete ICAO/WMO METAR specification or all national variations.
- Risk tags use entered planning thresholds and are not a regulatory go/no-go decision.
- Always use the complete current official weather briefing and competent operational review.
Worked examples checked against the calculator source on . These are reproducible calculation checks, not aircraft trials, site measurements or operational approval. Existing formula versions and technical review status remain as stated above.