The Winds and Temperatures Aloft Forecast, the FB Product, and How Four Little Digits Tell You Which Altitude Will Actually Get You There

The Winds and Temperatures Aloft Forecast - known in coded form as the FB product - tells you the wind direction, wind speed, and temperature at specific altitudes across the country, so you can predict how long a cross-country will take and how much fuel it will burn. Produced by the National Weather Service twice a day, each altitude is encoded in a short group of digits: the first two are wind direction (in true north), the next two are speed in knots, and the last two are temperature in Celsius. Once you can read those digits, you can choose the altitude with the least headwind or the strongest tailwind before you ever start the engine.

What Is the Winds and Temperatures Aloft Forecast (FB)?

Your weather briefing has a lot of moving parts. The METAR tells you what’s happening at the surface right now. The TAF tells you what a terminal is going to do. But neither one describes the thousands of feet of air you’ll actually spend your entire flight sitting in.

That’s what the winds aloft forecast is for. It answers the two questions that matter most on any cross-country: how long will this take, and how much fuel will it burn.

The official name is the Winds and Temperatures Aloft Forecast, and its coded identifier is FB. Most pilots just call it “the winds aloft” or “the FB” - same product. It’s computer-produced twice a day by the National Weather Service and forecasts wind direction, wind speed, and temperature at a stack of standard altitudes for locations across the country.

Those altitudes typically run 3,000, 6,000, 9,000, 12,000, 18,000, and 24,000 feet, and continue up to 39,000 feet and beyond for higher-performance aircraft.

How Do I Read a Winds Aloft Forecast?

Each location’s forecast is a row of numbers grouped by altitude. At each altitude you get a short code - usually six digits, sometimes just four. Here’s how to break one apart.

Say at 9,000 feet you see the group 2432+06.

• First two digits - wind direction: “24” means 240 degrees.
• Next two digits - wind speed: “32” means 32 knots.
• Last portion - temperature: “+06” means +6°C.

So the code reads: wind from 240 degrees at 32 knots, temperature +6°C. Direction, speed, temperature. Decode one and you’ve decoded them all.

One critical catch: that direction is referenced to true north, not magnetic. The FB is a forecast product generated by computers that think in true. Your METAR, your ATIS, and the tower talking to you are all magnetic. Before comparing the winds aloft to your magnetic heading, correct for magnetic variation - which might be around 10 degrees in some regions, more or less elsewhere, or near zero. Just remember: the winds aloft are true; the wind out the window is magnetic.

What Do the Weird Codes in the FB Mean?

The forecast has a handful of quirks that trip people up - and examiners love to test them. Here are the four to know.

1. No sign above 24,000 feet. Above 24,000 feet, the temperature is always below zero, so the forecast drops the minus sign to save characters. If a group at 30,000 feet shows a temperature of “52,” that’s –52°C.

2. “9900” means light and variable. When the forecast wind is less than 5 knots, there’s no meaningful direction, so it’s coded 9900. Don’t read that as a wind from 990 degrees - it means light and variable, essentially calm air. For cross-country planning, calm is good news if you were worried about a headwind.

3. Winds of 100 knots or more use a coding trick. Direction only goes up to 36 (360°), and the speed field only holds two digits (up to 99). So when the wind is 100 knots or more, the forecast adds 50 to the direction and subtracts 100 from the speed. If you see 7315, note that “73” is an impossible direction - that’s your flag. Subtract 50: 73 – 50 = 23, so the real direction is 230 degrees. Add 100 back to the speed: 15 + 100 = 115 knots. So 7315 means wind from 230 degrees at 115 knots - a jet stream, and the reason your airline flight home from the west coast runs faster than the flight out.

4. Blanks near the surface. The forecast won’t give winds for an altitude within about 1,500 feet of the station’s elevation, and won’t give a temperature within about 2,500 feet of the surface. Near the ground, wind behaves unpredictably from terrain, friction, and heating, so a forecast wouldn’t be reliable. At a high-elevation airport, a blank 3,000-foot line isn’t an error - the forecast just isn’t pretending to know.

Which Altitude Should I Fly Based on the Winds Aloft?

This is where the FB actually makes you a better pilot. The forecast hands you the answer to “which altitude?” before takeoff.

Picture a westbound flight on a course of roughly 270 degrees, with three legal, comfortable options: 3,000, 6,000, or 9,000 feet. The winds aloft show:

• 3,000 ft: from 240 at 15
• 6,000 ft: from 250 at 28
• 9,000 ft: from 260 at 40

Flying west, the wind at 9,000 is nearly on your nose at 40 knots - a stiff headwind. Down at 3,000, it’s 240 at 15: still mostly a headwind, but far weaker and more off to the side. Into the wind, lower is faster. Staying at 3,000 saves you 20-plus knots over a 200-mile leg - real time, real fuel, and the difference between comfortable reserves and sweating the gauge.

Now fly that same route home eastbound on a heading of 090. That same wind is now on your tail, so you want to climb and ride the strongest push you can reach. The 40-knot headwind at 9,000 becomes a 40-knot tailwind. Same air, opposite gift.

That’s the whole game:

• Into the wind: find the altitude with the least headwind (often lower).
• With the wind: find the altitude with the most tailwind (often higher).

Why Does the Temperature Column Matter?

The temperature column isn’t trivia - it does two jobs.

True airspeed. True airspeed climbs as the air gets colder and thinner, and your flight planning wants true airspeed, not indicated. The temperature at your cruise altitude feeds that calculation.

Freezing level and icing risk. Scan down the temperature column and find where it crosses from plus to minus - that’s your freezing level. If you’ll be flying through visible moisture (clouds, rain) at or above that altitude, you’re now thinking about structural icing. The winds aloft quietly told you the floor of the icing risk, and most pilots fly right past it looking only at the wind.

How Does This Fit the ACS and My Checkride?

Under weather information, the Airman Certification Standards (ACS) expect you to gather, read, analyze, and interpret the appropriate weather products - and the winds aloft is squarely one of them.

When an examiner hands you an FB forecast, they aren’t testing whether you can recite that “9900 means light and variable.” They’re testing whether you can look at the numbers and make a decision: which altitude, and why. That’s the answer that shows you’re a pilot, not just someone who passed a written test.

How to Fold the Winds Aloft Into Your Routine

Here’s the workflow - about 90 seconds of work per flight:

1. Get your standard briefing first. METARs, TAFs, the big-picture weather, and NOTAMs.
2. Pull the winds aloft for the station nearest your course, at the altitudes you’re actually considering.
3. Decode each candidate altitude: direction, speed, temperature.
4. Correct the true direction to magnetic before comparing it to your heading.
5. Compare the headwind or tailwind component at each altitude.
6. Pick the altitude that serves the flight - not just the one you fly out of habit.
7. Find your freezing level in the temperature column and file it away.

That’s the difference between the pilot who’s surprised on every cross-country and the one who knew, before takeoff, almost exactly what the clock and the fuel were going to do. This is one of the cheapest upgrades you’ll ever make to your flying - it costs nothing but the willingness to slow down and decode four little digits, and it pays back every flight.

The forecast comes straight from the National Weather Service, and the FAA’s Aviation Weather Handbook covers it in depth - free, and worth a slow read.

Key Takeaways

• The Winds and Temperatures Aloft Forecast (FB) is produced by the National Weather Service twice a day and gives wind direction, speed, and temperature at standard altitudes.
• Decode each group as direction (2 digits) + speed (2 digits) + temperature, and remember the direction is in true north - correct for magnetic variation before using it.
• Know the four quirks: no sign above 24,000 ft (always negative), 9900 = light and variable, add 50 / subtract 100 for winds of 100+ knots, and blanks near the surface.
• Into the wind, fly the altitude with the least headwind (often lower); with the wind, fly the one with the most tailwind (often higher).
• Use the temperature column for true airspeed and to locate the freezing level, the floor of your structural-icing risk.