What is the difference between winds aloft and surface winds?

Surface winds describe conditions at airport level and are used for takeoff, landing, and taxi planning. Winds aloft (FD winds) describe atmospheric winds at cruise altitudes - 3,000 feet MSL and above - and are used for in-flight navigation, altitude selection, and wind correction angle calculations.

How often is the Winds and Temperatures Aloft Forecast updated?

The forecast is issued twice daily, based on observation times at 0000Z and 1200Z, with valid periods of 12 and 24 hours. For any departure, use the most recent issuance whose valid time covers your planned flight window.

Why is wind direction in the winds aloft given in true degrees, not magnetic?

Atmospheric wind direction is a physical property of the air mass, measured against true north. Magnetic variation is a navigation correction applied by the pilot - it belongs in your heading calculations, not in the weather product itself.

What does it mean when a station is missing the 3,000 or 6,000-foot column?

When terrain at a reporting station is within 1,500 feet of a forecast altitude level, that altitude is omitted. In mountainous terrain, the lower altitude columns are frequently blank for certain stations. This is expected behavior, not a data error - the forecast level is at or below the ground.

How do I find the freezing level using winds aloft temperature data?

Scan the temperature column upward and find where the sign changes from positive to negative. The freezing level falls between the last positive-temperature altitude and the first negative-temperature altitude. With entries of +2°C at 9,000 feet and −4°C at 12,000 feet, you can interpolate an approximate freezing level within that range.

The Winds Aloft Forecast, the FD Winds Product That Can Save You an Hour on Any Cross-Country Flight, and the Altitude Math Your Examiner Expects You to Know

The Winds and Temperatures Aloft Forecast - commonly called FD winds - is a National Weather Service product that predicts wind direction, wind speed, and air temperature at specific altitudes above reporting stations across the country. Five minutes spent with this product during your preflight briefing can save thirty minutes in the air. It is one of the most actionable tools in a cross-country pilot’s weather toolkit.

What Is the Winds and Temperatures Aloft Forecast?

The winds aloft forecast is not a surface product. It describes what the atmosphere is doing at 3,000, 6,000, 9,000, 12,000, 18,000, 24,000 feet above mean sea level (and higher), at reporting stations scattered across the country - not what the wind sock is doing at your departure airport.

The forecast is issued twice per day, based on synoptic observation times at 0000Z and 1200Z. It is valid for 12 hours and 24 hours out. For a morning departure, use the most recent issuance with a valid time that covers your planned flight window.

Where Do You Find the FD Winds Product?

The official FD winds product is available through several sources:

1800wxbrief.com - standard FAA weather briefing
aviationweather.gov - under Winds and Temperatures Aloft
ForeFlight, Garmin Pilot, and most EFB applications include it in preflight weather packages

The designator “FD winds” is shorthand that carried over from the paper-teletype era. Instructors and controllers who learned before digital briefings still use it routinely.

How Do You Decode the FD Winds Encoded Format?

The raw forecast is organized by geographic station, then by altitude. For most general aviation cross-country flying, the 6,000, 9,000, and 12,000-foot columns are most relevant.

Each altitude entry is a six-character encoded string. Take a sample entry at 9,000 feet: 2132+04

First two digits (21): wind direction in tens of degrees - 210° true (wind from the southwest)
Second two digits (32): wind speed in knots - 32 knots
Sign and final two digits (+04): temperature in Celsius - +4°C

The complete reading: wind from 210° true at 32 knots, temperature +4°C. After decoding three or four entries by hand, the format becomes second nature.

What Are the Common Decoding Mistakes Pilots Make?

Mistake 1: Treating wind direction as magnetic. Wind direction in the winds aloft is always in degrees true. When applying it to navigation, convert using local magnetic variation. In an area with 10° easterly variation, a wind from 210° true becomes 200° magnetic - a small but real difference that compounds on every heading calculation in high-variation areas.

Mistake 2: Missing the high-wind encoding convention. When wind speed is 50 knots or higher, the NWS adds 50 to the direction code and subtracts 50 from the speed before encoding. If you see a direction value of 50 or higher in the encoded string, subtract 50 from those digits and add 50 to the speed digits.

Example: 7230 decodes as 220° true (72 − 50 = 22, meaning 220°) at 80 knots (30 + 50 = 80). This appears most often at jet stream altitudes but can occur at general aviation cruise altitudes during strong synoptic setups. Know it for both the written exam and the oral.

Two structural notes: Temperature data is not encoded at the 3,000-foot level - it starts at 6,000 feet and above. In mountainous terrain, the lower altitude columns may be omitted entirely for stations where terrain exceeds the forecast level. That is not a data error; the forecast altitude is simply below the ground.

How Do You Use Winds Aloft to Choose Your Cruise Altitude?

The wind at any given altitude directly affects your groundspeed. The difference between a 15-knot tailwind and a 15-knot headwind at a typical light single cruise speed is roughly 25–30% of total groundspeed - on a two-hour flight, that is nearly 30 minutes and meaningful additional fuel.

Here is a concrete example. A Cherokee with a cruise true airspeed of 118 knots is flying eastbound:

At 9,000 feet: winds from 270° at 25 knots - a direct headwind. Groundspeed drops to roughly 93 knots. A one-hour leg becomes a one-hour-sixteen-minute leg.
At 12,000 feet: winds from 330° at 15 knots - a northnorthwest wind with a headwind component of only 8–9 knots. Groundspeed rises to roughly 109–110 knots.

That is a 16-knot groundspeed difference between two altitudes. On a three-hour flight, 16 knots of groundspeed means arriving approximately 30 minutes earlier and burning roughly 1.5 gallons less fuel. That calculation takes two minutes in your briefing.

Altitude shopping on a real routing: Consider a flight from Kansas City to Albuquerque - roughly 700 nautical miles heading southwest. Pulling the winds aloft for stations along the route:

6,000 feet: winds from the south at 12 knots - crosswind with a slight tailwind component
9,000 feet: winds from the west at 28 knots - direct headwind on a southwestbound flight
12,000 feet: winds from the northwest at 18 knots - partial tailwind on a southwest heading

The choice is not automatic. The question is whether the fuel burn increase at the higher altitude costs more than the groundspeed gain recovers. The winds aloft forecast gives you the information to run that math on the ground, before you start the engine.

Why Does Temperature Data in the Winds Aloft Forecast Matter?

Most pilots focus on the wind columns and treat temperature as optional. It is not.

1. Estimating the freezing level. If the forecast at 9,000 feet shows +2°C and at 12,000 feet shows −4°C, the freezing level falls somewhere between those altitudes. For a VFR pilot without de-icing equipment, any cloud layer or precipitation in that zone is off limits. The winds aloft temperature column is what tells you where those limits are.

2. Density altitude at cruise. The standard atmosphere assumes a lapse rate of roughly 2°C per 1,000 feet. If temperatures at cruise altitude are significantly warmer than standard, true airspeed will be higher but engine output will be reduced. Performance calculations should reflect actual forecast temperatures.

3. Anticipating wind shear. A steep temperature inversion at a given altitude often coincides with a zone where wind speed or direction changes sharply over a short vertical distance. When the winds aloft show a large shift in direction or speed between two adjacent altitude levels and the temperature data shows an inversion in that layer, expect turbulence at the boundary. Pick one side of that transition - flying through the middle of a wind shear zone in a light aircraft is uncomfortable at best and can be a serious handful.

What Does Your Checkride Examiner Expect You to Know About Winds Aloft?

The Airman Certification Standards (ACS) includes winds and temperatures aloft as part of the weather elements a private pilot must understand and apply in cross-country planning. When an examiner asks why you chose your cruise altitude, the answer must include winds. “9,000 because that is what the hemispheric rule allows” leaves out the most important factor.

Examiners commonly hand candidates a winds aloft entry and a true course and ask them to calculate a wind correction angle. The process:

Take your true course, true airspeed, and the wind vector from the winds aloft
Use an E6B (mechanical or electronic) to solve for the heading needed to track your desired course
The difference between that heading and your true course is the wind correction angle
Apply local magnetic variation to convert to your compass heading

Common student error: using the surface wind for cruise-level calculations. The wind sock at the airport has nothing to do with what the air is doing at 9,000 feet. Surface wind is for takeoff and landing planning. Winds aloft is for everything in between.

How Should You Practice Winds Aloft Before Your Checkride?

Pull up the winds aloft for your home area on a day you are not flying. Find the reporting stations nearest to two airports you know well.

Decode three entries by hand - write out direction, speed, and temperature for each altitude level
Find the freezing level by locating where temperature crosses zero between adjacent levels
Plan a hypothetical routing between those two airports and determine which altitude the winds favor
Write down the reasoning - not just the number, but why

Do this on two different days with different weather patterns. By the time you are across from an examiner with a cross-country plan on the table, the product will be familiar territory rather than a source of anxiety.

Examiners are looking for a pilot who treats weather as a system. The METAR at the destination, the TAF for the alternate, the AIRMETs along the route, and the winds aloft are all pieces of that system. The good preflight briefing is the one where the story is coherent before you leave the ground.

Graphical Wind Products vs. the Official FD Winds

ForeFlight and similar apps display animated wind layers sourced from numerical weather models like the Rapid Refresh and the Global Forecast System. These graphics are useful, frequently accurate, and visually intuitive.

They are not the same product as the official Winds and Temperatures Aloft Forecast. The official FD winds product issued by the National Weather Service is the standard of record for preflight planning. Know how to read both, understand what each one represents, and when documenting your weather planning, cite the official product.

Key Takeaways

The FD winds product provides predicted wind direction, speed, and temperature at 3,000 through 24,000 feet MSL at reporting stations nationwide
Wind direction in winds aloft is always degrees true - apply local magnetic variation before using it in heading calculations
When wind speed is 50 knots or greater, the encoding adds 50 to the direction code and subtracts 50 from the speed; reverse that math to decode correctly
Temperature data starts at 6,000 feet and is used to estimate the freezing level, assess density altitude at cruise, and anticipate wind shear zones
On a three-hour cross-country, a 16-knot groundspeed difference between altitude choices can translate to 30 minutes and roughly 1.5 gallons of fuel - the altitude decision is always worth running the numbers