How to Read a TAF: A Pilot's Guide to Terminal Aerodrome Forecasts

If you're studying for your private pilot checkride or just trying to make sense of that wall of letters and numbers in your weather briefing, you're in the right place. A terminal aerodrome forecast (TAF) is one of the most important aviation weather reports you'll use throughout your flying career. This guide breaks down every element of a TAF so you can decode one quickly, confidently, and correctly.

Key Takeaways

• A TAF is a weather forecast (not an observation) that covers expected weather conditions within 5 statute miles of an airport's runway complex for 24 to 30 hours.
• TAFs are issued four times daily by the National Weather Service and share the same weather codes as METAR reports.
• Understanding the four change groups (FM, BECMG, TEMPO, PROB) is the key to reading how weather conditions will evolve over the TAF's valid period.
• Learning to read TAF reports is a core ground school skill tested on FAA knowledge exams and used in every flight planning session.

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What Is a TAF?

A TAF (terminal aerodrome forecast) is a concise, coded weather forecast issued for the area immediately surrounding an airport. According to the FAA's Aeronautical Information Manual, TAFs are prepared by 123 NWS Weather Forecast Offices for over 700 airports across the United States.

Unlike metar reports, which tell you what the actual weather is right now, a TAF tells you what the expected weather conditions will be over the next 24 to 30 hours. Think of it this way: a METAR is a snapshot, and a TAF is the movie trailer.

TAFs are scheduled four times daily, covering periods beginning at 0000Z, 0600Z, 1200Z, and 1800Z. Each routine forecast uses the same weather codes you'd find in a meteorological aerodrome report, so once you've learned to read METARs, you're already halfway there.

Breaking Down a TAF: Step by Step

The best way to learn how to read a TAF is to walk through a real example. Let's decode this sample TAF piece by piece:

TAF KPIT 091730Z 0918/1024 15005KT 5SM HZ FEW020 WS010/31022KT

Every TAF follows the same sequence of elements. Here's what each group means, reading left to right:

Let's dig deeper into each of these elements.

1. Report Type and Station Identifier

The communications header preceding every TAF starts with the report type. You'll see either TAF for a routine forecast or TAF AMD for an amended forecast. A corrected TAF will show TAF COR in the header.

The four-letter ICAO station identifier tells you which airport the forecast covers. In the U.S., these start with "K" (for example, KPIT for Pittsburgh, KORD for Chicago O'Hare, KPDX for Portland).

2. Issue Time

The issue time is a six-digit group followed by the letter Z (which stands for Zulu, or UTC). The first two digits are the day of the month, and the last four digits are the time in hours and minutes.

So 091730Z means this TAF was issued on the 9th at 1730 UTC.

3. The Valid Period Group

The valid period tells you exactly when the forecast begins and ends. It's formatted as two four-digit groups separated by a slash. The first two digits of each group are the date, and the last two digits are the hour in UTC.

0918/1024 means the forecast is valid from 1800 UTC on the 9th to 0000 UTC on the 11th (24 = midnight, which is 0000Z on the next day). This is a 30-hour TAF. Most TAFs cover a 24-hour valid period, but select major airports get 30-hour coverage.

Pro Tip: The valid period date format trips up a lot of students. Remember, the first two digits are always the day, not the time. So "0918" is NOT 0918 Zulu. It's the 9th day at 1800Z.

4. Forecast Wind

Wind is always the first weather data element in the initial forecast. It's coded as a five-digit group (or six digits if speed exceeds 99 knots) followed by KT for knots.

• The first three digits are the true wind direction (the direction the wind is blowing from), rounded to the nearest 10 degrees.
• The next two digits are the forecast wind speed in knots.
• If wind gusts are expected, you'll see a G followed by the gust speed (e.g., 24015G25KT means wind from 240° at 15 knots, gusting to 25).
• Calm winds are coded as 00000KT.
• Variable winds with no clear forecast wind direction are coded as VRB followed by the speed.

The forecast wind direction is always referenced to true north, not magnetic north. This is important to remember when calculating crosswind components for a specific runway.

5. Prevailing Visibility

Visibility in U.S. TAFs is reported in statute miles followed by SM. If visibility is expected to be 6 miles or greater, you'll see P6SM (the "P" stands for "plus").

Lower visibility values are reported as specific numbers (e.g., 3SM, 1SM, 1/2SM). These values are critical for determining whether visual flight rules or instrument flight rules will apply at your destination.

6. Weather Phenomena and Weather Codes

After visibility comes the significant weather group. This is where weather phenomena like rain, snow, fog, and thunderstorms are encoded. TAFs use the exact same weather codes as METARs, structured in this order:

Intensity → Descriptor → Precipitation/Obscuration/Other

Here's a quick-reference table of the most common weather codes you'll see in aviation weather reports:

So if you see -SHRA in a TAF, that's light rain showers. +TSRA means heavy thunderstorms with rain. FZRA means freezing rain. And -RA BR means light rain and mist.

When no significant weather is expected, the weather group is simply omitted. If weather was previously forecast and is expected to end, you'll see NSW (No Significant Weather).

Pro Tip: The NWS METAR/TAF decode key is a great reference to keep handy while you're still memorizing these codes. Print it out and stick it in your flight bag.

7. Sky Condition Group

The sky condition group tells you about cloud cover and ceiling height. Cloud amounts are reported using these codes:

• SKC = Sky clear
• FEW = Few clouds (1/8 to 2/8 coverage)
• SCT = Scattered clouds (3/8 to 4/8 coverage)
• BKN = Broken clouds (5/8 to 7/8 coverage)
• OVC = Overcast (8/8 coverage)

The three-digit number after the cloud amount is the height in hundreds of feet above ground level (AGL). So BKN030 means a broken cloud layer at 3,000 feet AGL, and OVC010 means an overcast cloud deck at 1,000 feet.

Your ceiling is defined as the lowest layer reported as broken or overcast. Few clouds and scattered clouds do not count as a ceiling. This distinction matters because ceiling height determines your flight category (VFR, MVFR, IFR, or LIFR).

If cumulonimbus clouds are expected, you'll see CB appended to the cloud group (e.g., BKN015CB). This is a major red flag for thunderstorms, severe turbulence, and heavy precipitation.

When the sky is completely obscured (such as in dense fog), vertical visibility is reported as VV followed by a three-digit height (e.g., VV008 = vertical visibility 800 feet).

8. Optional Data: Wind Shear

Some TAFs include a wind shear group, which forecasts non-convective low-level wind shear up to 2,000 feet AGL. It's formatted as WS followed by a three-digit height, a slash, and then the wind direction and speed at that height.

For example, WS010/31022KT means wind shear is expected at 1,000 feet AGL, with winds from 310° at 22 knots at that altitude. This is critical information for approach and departure planning, and it's a key element of risk management during flight planning.

Understanding TAF Change Groups

Here's where reading a TAF gets interesting. The initial forecast tells you what conditions look like at the start of the valid period, but weather changes. TAFs use four change group indicators to describe how conditions will evolve. This is the section that separates students who sort of understand TAFs from those who truly know how to read a TAF.

FM (From): The Clean Break

An FM group signals a rapid, significant change that essentially replaces everything before it. It's coded as FM followed by a six-digit date/hour/minute group.

FM091930 30015G25KT 3SM SHRA OVC015

This means: starting at 1930 UTC on the 9th, expect wind from 300° at 15 knots with wind gusts to 25 knots, visibility 3 statute miles in rain showers, and an overcast sky condition at 1,500 feet. Every element from the initial forecast is replaced. Think of FM as a hard reset.

Every FM group starts on a new line and includes all required elements (wind, visibility, weather, sky condition). Nothing carries over from the previous forecast change.

BECMG (Becoming): The Slow Shift

BECMG describes a gradual but permanent change that takes place over a specified time window. It's coded as BECMG followed by two four-digit date/hour groups.

BECMG 1013/1015 P6SM NSW SKC

This means: between 1300Z and 1500Z on the 10th, conditions will gradually improve to visibility greater than 6 statute miles, no significant weather, and sky clear. After 1500Z, these become the new prevailing conditions and stay that way.

Unlike FM, a BECMG group includes only the elements that are changing. Anything not mentioned carries forward from the previous forecast.

TEMPO (Temporary): The Brief Interruption

TEMPO is used for conditions expected to last less than one hour at a time and to occur during less than half of the specified time period. It's coded as TEMPO followed by two four-digit date/hour groups.

TEMPO 0920/0922 1/2SM +TSRA OVC008CB

This means: between 2000Z and 2200Z on the 9th, expect temporary periods of visibility dropping to 1/2 statute mile in heavy thunderstorms with rain and an overcast cloud deck at 800 feet with cumulonimbus. These are brief interruptions. After each occurrence, conditions snap back to the prevailing forecast.

Only the elements expected to change temporarily are listed. The current forecast for wind, for example, would remain unchanged during TEMPO periods unless a new wind is specified.

Pro Tip: A common ground school mistake is confusing BECMG with TEMPO. Here's the simple rule: BECMG is a one-way ticket (conditions change and stay changed). TEMPO is a round trip (conditions change briefly, then revert). Knowing this distinction is huge for flight planning and checkride prep.

PROB (Probability): The "Maybe"

PROB groups express a 30% or 40% probability of specific weather conditions occurring. You'll see either PROB30 or PROB40, often combined with TEMPO.

PROB40 0600/0606 2SM TSRA OVC008CB

This means: there's a 40% chance that between 0000Z and 0600Z on the 6th, conditions will temporarily include visibility of 2 statute miles in thunderstorms with rain and an overcast cumulonimbus layer at 800 feet.

PROB groups are typically reserved for thunderstorms and poor visibility from fog, mist, or other obscurations. The FAA does not use PROB in the first nine hours of a TAF. Probabilities below 30% aren't mentioned at all, and anything 50% or higher gets included as part of the main forecast.

How TAFs Fit Into Flight Planning

Reading a TAF isn't just an academic exercise for ground school. It's a practical skill you'll use before every flight to check expected weather conditions at your departure, destination, and alternate airports.

Here's how TAFs connect to bigger-picture weather data and flight planning:

• TAF vs. METAR: The METAR gives you current weather data. The TAF gives you the forecast. Use both together. If the METAR is showing conditions deteriorating faster than the TAF predicted, that's a significant change worth paying attention to.
• Graphical forecasts and significant weather charts provide regional context. TAFs are point-specific, covering only the elements within about 5 statute miles of the airport. For the big picture, pair your TAF with graphical forecasts from the Aviation Weather Center.
• Alternate airport planning: Under instrument flight rules, you'll use TAFs to determine whether your destination and alternate airports meet required ceiling and visibility minimums. TEMPO and PROB conditions play a role in these calculations.
• Significant meteorological information (SIGMETs) and airmen's meteorological information (AIRMETs) cover en route hazards like severe icing, moderate turbulence, and sustained surface winds of 30 knots or more. TAFs cover the terminal area. Use them together for a complete weather picture.

If you're training to become a pilot, weather services like TAFs and METARs are covered in depth during your ground school coursework. Understanding how flight school works will give you a better picture of how this fits into your overall training.

Sample TAF: Full Decode

Let's put it all together with a complete TAF and walk through the current forecast from start to finish:

TAF KORD 051130Z 0512/0618 14008KT 5SM BR BKN030
TEMPO 0513/0516 1 1/2SM BR
FM051600 16010KT P6SM SKC
FM052300 20013G20KT 4SM SHRA OVC020
PROB40 0600/0606 2SM TSRA OVC008CB
BECMG 0606/0608 21015KT P6SM NSW SCT040

Here's the decoded timeline:

1. 0512 to 0516 (1200Z-1600Z on the 5th): Wind from 140° at 8 knots, visibility 5 statute miles in mist, broken clouds at 3,000 feet. Temporary drops to 1.5 statute miles in mist between 1300Z and 1600Z.
2. FM051600 (1600Z on the 5th onward): Wind shifts to 160° at 10 knots, visibility improves to greater than 6 statute miles, sky clear. A clean break from previous conditions.
3. FM052300 (2300Z on the 5th onward): Wind shifts again to 200° at 13 knots with gusts to 20 knots, visibility drops to 4 statute miles in rain showers, overcast at 2,000 feet.
4. PROB40 0600/0606 (0000Z-0600Z on the 6th): 40% chance of temporary drops to 2 statute miles in thunderstorms with rain, overcast cloud deck at 800 feet with cumulonimbus.
5. BECMG 0606/0608 (0600Z-0800Z on the 6th): Gradual improvement to wind from 210° at 15 knots, visibility greater than 6 statute miles, no significant weather, scattered clouds at 4,000 feet.

By building this mental timeline, you know exactly when the worst weather is expected and can plan your flight around it. That's the real power of knowing how to read a TAF.

Frequently Asked Questions

What does TAF stand for in aviation?

TAF stands for terminal aerodrome forecast. It's a coded weather forecast issued by the National Weather Service that predicts expected weather conditions at a specific airport for the next 24 to 30 hours.

What is the difference between a TAF and a METAR?

A METAR (meteorological aerodrome report) reports actual weather conditions observed at an airport at a specific time. A TAF forecasts expected weather for the upcoming 24 to 30 hours. METARs are observations. TAFs are forecasts. Both use the same weather codes for wind, visibility, weather phenomena, and sky condition.

What does the World Meteorological Organization have to do with TAFs?

The World Meteorological Organization (WMO) established the standardized coding system used for both METARs and TAFs. This ensures pilots worldwide can read and interpret the same weather reporting format, regardless of which country issued the report.

What do forecast icing and moderate icing codes look like in a TAF?

Standard civilian TAFs in the U.S. don't typically include specific forecast icing or moderate icing codes within the TAF body itself. Icing forecasts are generally found in AIRMETs, SIGMETs, and graphical forecasts. If you see an icing layer referenced, it may be in a military TAF extension or a supplementary product. For icing risk, check the AIRMET Zulu product alongside your TAF.

What about severe turbulence and severe icing?

Like icing, severe turbulence and severe icing are not coded directly in standard U.S. TAFs. These hazards are communicated through SIGMETs, which are issued when severe icing not associated with thunderstorms or severe turbulence is expected along your route. Always cross-reference your TAF with SIGMET products and graphical forecasts for a complete picture of significant change winds aloft and en route hazards.

What is the altimeter setting in a TAF?

Standard U.S. TAFs do not include an altimeter setting. The altimeter setting is found in METAR reports, coded as A followed by four digits representing inches of mercury (e.g., A2992 = 29.92 inHg). Some international TAFs include QNH (pressure in hectopascals), but this is not standard practice in U.S. TAFs.

What are the flight categories based on ceiling and visibility?

Flight categories help pilots quickly assess whether conditions are suitable for VFR or IFR:

• VFR: Ceiling above 3,000 feet and visibility greater than 5 statute miles
• MVFR (Marginal VFR): Ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 statute miles
• IFR: Ceiling 500 to below 1,000 feet and/or visibility 1 to below 3 statute miles
• LIFR (Low IFR): Ceiling below 500 feet and/or visibility below 1 statute mile

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