How to Read a TAF Weather Forecast

What You’ll Need

A TAF for the airport and date you care about, obtained from an official aviation weather service or flight-planning source.
The airport’s four-letter ICAO identifier. In the contiguous United States, it commonly begins with K; some US locations use other prefixes.
A UTC-to-local-time reference and, if the report is abbreviated, a guide to standard aviation weather codes.
For an operational flight decision, current training, approved flight-planning tools, and the applicable official briefing. This guide explains the format; it is not a substitute for training or an authoritative briefing.

Step-by-Step

Confirm the airport. Find the four-letter identifier near the start of the report, such as KDEN for Denver International Airport. Check that it matches the airport you intend to assess; a nearby airport’s forecast may not describe conditions at your destination.
Read the report type and issue time. A routine terminal forecast often begins with TAF. The next date-and-time group, usually six digits followed by Z, indicates when it was issued: the first two digits are the day of the month, and the remaining four are the UTC hour and minute. Some reports include amendment or correction markers such as AMD or COR. Use the latest valid report and do not mistake its issue time for its start time.
Check the validity period. The group after the airport identifier commonly looks like 0912/1012. It means the forecast is valid from 1200 UTC on the ninth day through 1200 UTC on the tenth. The first two digits are the start day and time; the last four digits give the end day and time. Month boundaries can make the month less obvious, so check the report date and source display.
Convert UTC to local time carefully. The Z after a time means Zulu time, another name for UTC. Convert both the forecast period and any changes to the time at the airport, accounting for daylight saving time where applicable. Do not assume the airport’s local time zone or a fixed offset. If you cannot verify the conversion, keep the timeline in UTC.
Decode the initial wind. Wind is usually shown as three digits for direction in degrees true, followed by speed in knots: 18012KT means wind from 180 degrees at 12 knots. A suffix such as G20KT indicates gusts to 20 knots. VRB means variable direction; 00000KT means calm. A direction written as 180 is from the south, not blowing toward the south.
Read visibility and weather. Visibility may be shown in statute miles in US reports, sometimes as a fraction, followed by SM. For example, 3SM means three statute miles. Codes after it describe phenomena: RA is rain, SN snow, BR mist, FG fog, and TS thunderstorms. A minus sign indicates light intensity and a plus sign heavy intensity; no sign generally means moderate intensity. Check the source’s legend, because not every abbreviation is self-explanatory.
Interpret the cloud group and ceiling. Cloud groups combine coverage, cloud-base height in hundreds of feet above ground level, and sometimes a cloud type. FEW means few clouds, SCT scattered, BKN broken, and OVC overcast. Thus BKN020 means a broken layer based at 2,000 feet. For aviation weather, a ceiling is generally the lowest broken or overcast layer, or vertical visibility into an obscuration. A cloud base is not automatically a ceiling if the layer is only few or scattered.
Follow every change group in order. TAFs forecast change over time. FM means a relatively quick change beginning at the stated time; TEMPO marks temporary conditions expected within a time window; BECMG indicates conditions becoming established during a transition period; PROB30 or PROB40 signals a stated probability of specified conditions. Read each group’s time first, then its wind, visibility, weather, and clouds. Conditions in a new group may replace earlier elements, while omitted elements generally carry forward according to the TAF format.
Check special remarks and the end marker. Read any remarks after RMK, but remember that remarks may not be present. The report may end with an equal sign. Confirm that you have read the entire forecast, including any later change groups, rather than stopping at the first line break or first set of conditions.
Compare the forecast with current observations. A TAF is a forecast, not a live observation. Check the airport’s current METAR and relevant advisories as well, and note when each was issued. If you are making a flight decision, consult official sources and follow applicable procedures and training.

Common Mistakes

Mixing up report and validity times: The issue time says when the forecast was prepared; the validity group says when it applies.
Reading UTC as local time: A time ending in Z is UTC, even when a website also displays a local time.
Treating wind direction as where wind is going: Aviation wind direction describes where it comes from.
Calling every cloud layer a ceiling: FEW and SCT do not by themselves establish a ceiling under the usual definition.
Ignoring change groups: Conditions at the beginning of a TAF may differ substantially from those forecast later.
Assuming the forecast guarantees conditions: A TAF is an informed forecast for a defined area and period; actual weather can differ.

Tips

Read from left to right and make a simple timeline before interpreting individual details.
Write down the forecast’s start and end in UTC first, then convert the times you need.
Separate the basic conditions from each FM, TEMPO, BECMG, or probability group. This makes it easier to see when a change applies.
Use an official source’s legend when a code, visibility format, or amendment marker is unfamiliar. Display formats and supplementary notes can vary.
Look at the whole weather picture: wind, visibility, precipitation, cloud layers, and changes all matter. Do not judge a forecast from a single number.

Troubleshooting

The airport code does not look familiar: Search by the airport name in an official weather tool, then verify the identifier. Do not guess based on a city name, since one city may have multiple airports.

The date appears impossible: TAF time groups may cross midnight or a month boundary. Check the issue date, validity period, and source’s UTC display before converting; ask an aviation weather specialist if the timeline remains unclear.

You cannot decode a group: Copy the complete group, including its preceding change marker, and consult the official code guide. A missing symbol can change the meaning, so avoid interpreting an isolated fragment.

The TAF conflicts with current weather: Confirm that both reports are for the same airport and compare their observation or issue times. Weather changes, and a newer observation does not necessarily mean the forecast has been updated. Check current official products and advisories.

The report is missing or expired: Refresh the official source and verify the airport and date. Do not rely on an expired forecast or substitute a neighboring airport’s TAF without understanding the limitations.

Frequently Asked Questions

What does TAF stand for?

TAF stands for Terminal Aerodrome Forecast. It gives expected weather for an airport and the surrounding area used for aviation planning.

How long is a TAF valid?

The validity period is printed in the forecast and varies by report. Read the start and end group rather than assuming every TAF covers the same number of hours.

What does 9999 mean in a TAF?

In many international-format reports, 9999 means visibility of 10 kilometers or more. US reports commonly use statute-mile visibility formats instead, so interpret the group in the context of the report’s format.

What is the difference between a TAF and a METAR?

A TAF forecasts expected conditions for an airport over a validity period. A METAR reports observed weather at an airport at a particular time.

Can I use a TAF alone to decide whether to fly?

No. A TAF is only one part of aviation weather information, and it does not replace an official briefing, current observations, advisories, flight-planning requirements, or proper training.

What does TEMPO mean in a TAF?

TEMPO marks temporary conditions expected during the time window that follows. It does not mean those conditions will persist throughout the entire window.

Further reading: NOAA National Weather Service. Details can change, so check the official page for anything that matters to you. Spotted a mistake? Tell us. How we write an answer.