Where do I find the winds and temperatures aloft forecast?

The FB is available on 1800wxbrief.gov, ForeFlight, SkyVector, and most aviation weather sources. It's issued by the Aviation Weather Center four times daily.

Why is there no winds aloft data for low altitudes near a station?

The FB omits data for the surface and any altitude within 1,500 feet of the station's field elevation. Surface wind information comes from the METAR instead.

What does 9900 mean in a winds aloft forecast?

It indicates light and variable winds — speed below 5 knots with no predictable direction. Wind is not a significant planning factor at that altitude.

Should I always pick the altitude with the best groundspeed?

Not necessarily. Consider fuel burned in the climb, temperature and oxygen needs at higher altitudes, and ride quality. A slightly slower groundspeed at a smoother altitude can be the better choice.

How accurate is the winds aloft forecast?

The 6-hour and 12-hour forecasts are generally reliable. The 24-hour forecast is less dependable, especially near fronts. Always verify with GPS groundspeed once airborne and adjust your plan as needed.

Reading the winds and temperatures aloft forecast and picking the altitude that actually gets you there faster

The winds and temperatures aloft forecast (FB) is one of the most practical yet underused tools in a pilot’s weather briefing. By learning to decode its compact format and compare wind components across altitudes, you can choose a cruising altitude that delivers better groundspeed, lower fuel burn, and a more comfortable ride — not just one that satisfies the hemispheric rule.

What Is the Winds and Temperatures Aloft Forecast?

The FB (Foxtrot Bravo) is issued by the Aviation Weather Center and provides forecast wind direction, wind speed, and temperature at standard altitudes for stations across the country. You can find it on 1800wxbrief.gov, ForeFlight, SkyVector, and other weather sources.

The standard altitudes are 3,000, 6,000, 9,000, 12,000, 18,000, 24,000, 30,000, 34,000, and 39,000 feet. For VFR flying in a trainer, you’ll typically focus on 3,000 through 12,000 feet.

One important detail: the FB does not include surface winds or any altitude within 1,500 feet of the station elevation. Surface winds come from the METAR.

How Do You Decode the Numbers?

Each entry is either four or six digits.

Four digits (e.g., 2715): The first two digits are wind direction in tens of degrees, the last two are speed in knots. So 2715 means wind from 270 degrees at 15 knots.
Six digits (e.g., 2715-08): Same wind data plus temperature. The -08 means minus 8°C at that altitude.

Two special cases to know:

9900 means light and variable — wind speed is below 5 knots, direction unpredictable. Wind won’t be a factor at that altitude.
Speeds above 99 knots: The encoding adds 50 to the direction and subtracts 100 from the speed. An entry like 7308 decodes to 230 degrees at 108 knots (73 minus 50 = 23; 08 plus 100 = 108). You won’t encounter this at typical VFR altitudes, but it explains why upper-level entries look strange.

How Do You Pick the Best Cruise Altitude?

This is where the FB becomes a real planning tool. The process:

Identify three candidate altitudes — your minimum safe altitude, one step above, and one more above that.
Calculate the headwind or tailwind component at each altitude relative to your true course using an E6B or electronic flight computer.
Compare groundspeeds and pick the winner.

The math doesn’t have to be complicated. Plug in your true course, the wind direction and speed, and the computer gives you a wind correction angle and groundspeed.

A Real-World Example: Central Texas to Tulsa

Heading north-northeast, here’s what the FB might show:

6,000 ft — 1825 (wind from 180° at 25 kt): Nearly a pure tailwind. In a Cessna 172 cruising at 110 KTAS, groundspeed is roughly 135 knots.
9,000 ft — 2130 (wind from 210° at 30 kt): Tailwind component drops to about 20 knots after accounting for angle, but thinner air bumps TAS to ~115 kt. Groundspeed: ~135 knots.
12,000 ft — 2440 (wind from 240° at 40 kt): More crosswind than tailwind for a northbound course. Tailwind component maybe 15 knots, TAS ~120 kt. Groundspeed: ~135 knots — but you’ve burned more fuel climbing, the cockpit is colder, and supplemental oxygen may be needed on a long flight.

Six thousand feet wins. Same groundspeed, less fuel, more comfort, no oxygen concerns.

Why the Return Trip Needs a Different Altitude

Flip that same scenario southbound. The 180° wind at 6,000 feet is now a direct 25-knot headwind, dropping groundspeed to 85 knots. A two-hour trip becomes nearly three hours.

Check the alternatives:

9,000 ft: The 210° wind is more crosswind for a southbound course. Headwind component drops to ~20 knots. Groundspeed: ~95 knots.
12,000 ft: The 240° wind is nearly pure crosswind headed south. Headwind component may be only 5–10 knots. Groundspeed: 110+ knots.

Suddenly twelve thousand — the worst choice going north — is the best choice coming home. The altitude that works outbound is almost never the best altitude for the return.

What Does Temperature Tell You?

The temperature data in the FB matters beyond cockpit comfort:

Density altitude at cruise affects your true airspeed. Higher temps mean higher density altitude and reduced performance.
Icing risk: If the forecast temperature at your altitude is between 0°C and -20°C and there’s visible moisture, conditions favor structural icing. This matters even for VFR pilots flying near cloud bases.

When Should You Ignore Groundspeed and Prioritize Ride Quality?

When the FB shows strong winds at all altitudes — say 30 to 40 knots — the instinct is to stay low. But strong winds aloft often produce turbulence near the surface, especially over terrain. A 30-knot headwind at 9,000 feet may deliver a much smoother ride than 3,500 feet where those winds churn over hills and thermals.

Factor in ride quality. You’ll arrive less fatigued, and your passengers will thank you.

How Reliable Is the Forecast?

The FB is issued four times daily with valid periods extending to 24 hours. The 6-hour and 12-hour forecasts are fairly reliable. The 24-hour forecast is less dependable, especially near frontal boundaries.

Once airborne, verify with your GPS groundspeed. If you planned for a 10-knot tailwind but your groundspeed is below your TAS, the forecast was off. Adjust — change altitude, revise fuel planning, or both. The forecast gives you a solid starting plan; real-world data keeps you safe.

What Will the Examiner Want to See?

During the cross-country planning portion of the private pilot checkride, the Airman Certification Standards require you to obtain, read, and analyze weather information including winds aloft. The examiner wants to see that you:

Decoded the FB correctly
Used the winds to calculate a wind correction angle
Determined a realistic groundspeed
Computed accurate time en route and fuel burn

Simply picking an altitude and plugging in TAS without accounting for wind is a miss.

Key Takeaways

Decode the FB format: First two digits = wind direction (×10), next two = speed in knots, optional last digits = temperature in °C.
Compare three altitudes on every cross-country: minimum safe, one above, and one more. Calculate groundspeed for each and pick the best.
Plan different altitudes for outbound and return legs — winds shift in direction and speed with altitude.
Use temperature data to assess density altitude effects on TAS and potential icing risk.
Verify in flight — GPS groundspeed is ground truth. Adjust your plan when reality differs from the forecast.