NATO Color Codes for Aviation Weather — Now in metar.cloud

metar.cloud now supports NATO color codes alongside the traditional FAA flight categories. You can switch between the two in the settings menu — pick whichever system you prefer and the entire app updates: map markers, airport badges, and detail views all reflect your choice.

Why Two Systems?

The FAA system groups weather into four categories — VFR, MVFR, IFR, and LIFR — based on ceiling and visibility. It's simple and widely used in US general aviation.

The NATO system is used by military airfields across Europe and NATO member states. It has seven levels instead of four, giving a more granular picture of conditions. If you've flown in Europe or out of a military field, you've seen these color codes on METARs and airfield status boards.

The NATO Color Scale

NATO assigns a color state based on two factors: visibility and cloud ceiling (defined as the lowest layer with 3/8 coverage or more — SCT, BKN, or OVC). The worst of the two determines the final color.

Here are the thresholds:

Color	Ceiling	Visibility
BLU (Blue)	≥ 2,500 ft	≥ 8 km
WHT (White)	≥ 1,500 ft	≥ 5 km
GRN (Green)	≥ 700 ft	≥ 3,700 m
YLO1 (Yellow 1)	≥ 500 ft	≥ 2,500 m
YLO2 (Yellow 2)	≥ 300 ft	≥ 1,600 m
AMB (Amber)	≥ 200 ft	≥ 800 m
RED	< 200 ft	< 800 m

How It Works as a Grid

The chart below shows how ceiling and visibility combine. Find your ceiling row, find your visibility column — the cell where they meet is your color state. Then take the worst (lowest) of the two.

              VISIBILITY
              800m   1600m  2500m  3700m  5000m  8km+
          ┌──────────────────────────────────────────┐
  2500ft+ │  RED    AMB    YLO2   YLO1   WHT    BLU │
  1500ft  │  RED    AMB    YLO2   YLO1   WHT    WHT │
   700ft  │  RED    AMB    YLO2   YLO1   GRN    GRN │
   500ft  │  RED    AMB    YLO2   YLO1   YLO1   YLO1│
   300ft  │  RED    AMB    YLO2   YLO2   YLO2   YLO2│
   200ft  │  RED    AMB    AMB    AMB    AMB    AMB │
  <200ft  │  RED    RED    RED    RED    RED    RED │
          └──────────────────────────────────────────┘

  C        Cloud ceiling (lowest BKN/OVC layer)
  E
  I        Rule: take the WORST of the two values.
  L        e.g. ceiling 2500ft (BLU) + visibility 2km (YLO2) → YLO2
  I
  N
  G

For example, if the ceiling is 2,500 ft (BLU level) but visibility is only 2,000 m (YLO2 level), the overall color state is YLO2 — the worse of the two.

Quick Tutorial: Determining the Color Code

Let's walk through a real METAR:

METAR EGLL 101050Z 24008KT 4000 BKN008 09/08 Q1022

Step 1 — Find the visibility. 4000 means 4,000 meters. Looking at the table: 4,000 m is above 3,700 m but below 5,000 m → YLO1 for visibility.

Step 2 — Find the ceiling. BKN008 is a broken layer at 800 ft. That's the ceiling (first BKN or OVC layer). 800 ft is above 700 ft but below 1,500 ft → GRN for ceiling.

Step 3 — Take the worst. YLO1 is worse than GRN → final color state is YLO1.

Let's try another:

METAR EDDM 101020Z 09004KT 0600 FG VV001 02/02 Q1025

Visibility: 600 m → below 800 m → RED
Ceiling: VV001 (vertical visibility 100 ft, treated as ceiling) → below 200 ft → RED
Final: RED

And one more for good measure:

METAR LSZH 101050Z 18012KT 9999 FEW035 BKN100 14/06 Q1018

Visibility: 9999 (10 km+) → BLU
Ceiling: BKN100 is 10,000 ft → BLU
Final: BLU — excellent conditions.

NATO vs FAA: A Quick Comparison

NATO	Rough FAA Equivalent	Conditions
BLU	VFR	Clear, high ceiling, great visibility
WHT	VFR	Good VFR, slight limitations
GRN	MVFR (upper)	Moderate restrictions
YLO1	MVFR / IFR boundary	Approaching instrument conditions
YLO2	IFR	Instrument conditions
AMB	IFR	Low instrument conditions
RED	LIFR	Severe restrictions, most ops suspended

The mapping is approximate — the systems use different thresholds so they don't align perfectly.

How to Switch in metar.cloud

Open the settings menu (gear icon) and look for Color Scheme. You'll see two options:

FAA (Default) — VFR / MVFR / IFR / LIFR
NATO — BLU / WHT / GRN / YLO1 / YLO2 / AMB / RED

Your choice is saved and applied everywhere — the map, airport detail views, and flight category badges all update instantly. Try both and see which gives you a better feel for conditions at a glance.

Why It Matters

For pilots operating in Europe or on NATO airfields, the color code system is second nature. Having it in metar.cloud means you don't have to mentally translate between systems. And even if you're used to FAA categories, the finer granularity of seven levels (vs four) can be useful — it's easier to spot the difference between "low but flyable" (YLO1) and "probably not going anywhere" (AMB).

Fly safe, and check your colors before you go.