TAF (TAF AMD is Amended Forecast when included) 

KPIT 091730Z 091818 22020KT 3SM -SHRA BKN020

FM2030 30015G25KT 3SM SHRA OVC015 TEMPO 2022 1/2SM

TSRA OVC008CB

FM0100 27008KT 5SM -SHRA BKN020 OVC040 PROB40 0407

00000KT 1SM -RA BR

FM1000 22010KT 5SM -SHRA OVC020 BECMG 1315 20010KT

P6SM NSW SKC

Once you know how to pick out the TAF forecast time periods, the same logical sequence that we saw in METAR will follow. Below, a TAF is broken down to highlight its individual segments. Key words, and their definitions, indicating a new time period has started are highlighted in red.

TAF
 

KPIT 091730Z 091818 22020KT 3SM -SHRA BKN020

FM2030 30015G25KT 3SM SHRA OVC015 WS015/30045KT

TEMPO 2022 1/2SM TSRA OVC008CB

FM2300 27008KT 5SM -SHRA BKN020 OVC040 PROB40 0407

00000KT 1SM -RA BR

FM1000 22010KT 5SM -SHRA OVC020 BECMG 1315 20010KT

P6SM NSW SKC

The Where, When, and Wind trick works with TAF, too. There's a little twist with the "when," however. 

TAF

KPIT 091730Z 091818 22020KT

WHERE

KPIT is the ICAO station identifier. The usual 3 letter identifiers we are all familiar with preceded by a "K" for the contiguous United States. Alaska and Hawaii will use 4 letter identifiers beginning with "PA" and "PH" respectively. Changes are planned to incorporate three letter identifiers for those weather reporting stations where numbers and letters are now used (e.g., W10 to KHEF).

WHEN

091730Z This is the forecast for the 9th day of the month with an issuance time of 1730Z or UTC. This is a 2 digit date and 4 digit time. 

091818 is the valid period with the first two digits containing the day of the month (09).

091818 the second two digits specify the hour beginning the forecast period (1800Z). 

091818 the last two digits are the hour ending the forecast period (1800Z on the next day, (the 10th).

WIND

22020KT

See description under METAR

WS015/30045KT means at 1500 feet we expect wind to be 300 degrees at 45 KT. This indicates low level wind shear, not associated with convective activity. 

Time Periods, Etc.

FM2030 From 2030Z or UTC time. Indicates hours and minutes. 

TEMPO 2022 Temporary changes expected between 2000Z and 2200Z. 

FM2300 FROM 2300Z.

PROB40 0407 There is a 40 percent probability of this condition occurring between 0400Z and 0700Z. 

FM1000 FROM 1000Z. 

BECMG 1315 Conditions Becoming as described between 1300Z and 1500Z. 

Once the specific time periods can be discerned, the sequence of wind, visibility, significant weather, cloud cover and cloud height follows and is repeated for each time block. The only exception is after qualifiers such as PROB40, TEMPO, and BECMG, some of the components may be omitted if these are not expected to change. Notice after TEMPO 2022, there is no wind given and after PROB40 0407, there is no cloud cover listed. Note: When No Significant Weather (NSW) appears it only indicates obstruction to visibility or precipitation previously noted has ended. 
(See Abbreviations Section)

International Differences

Pilots and operators who fly to international destinations are cautioned to be alert to differences between U.S. METAR/TAF and international METAR/TAF. Some key differences follow. 

Altimeter Setting

The United States reports the altimeter setting in inches of mercury (e.g., A2992) and internationally it will be reported in hectoPascals (milibars) (e.g., Q1016). 

Wind

Internationally wind may be reported in knots (KT), kilometers per hour (KMH) or meters per second (MPS). Appropriate units are indicated on both METAR and TAF. 

Wind Shear

Low level wind shear, not associated with convective activity (e.g., WS015/30045KT, see TAF) will appear in TAFs in the United States, Canada, and Mexico only. 

Visibility

Internationally, visibility is reported in 4 digits using meters with the direction of the lowest visibility sector (e.g., 6000SW - meaning visibility is lowest at 6000 meters to the southwest). In the United States, we use prevailing visibility, in statute miles, not the lowest visibility, so the same conditions would be reported differently. 

International visibility reports also contain a trend such as:

D Down 

U Up 

N No change 

V Variable 

Other

Remarks (RMK) included in U.S. METAR are transmitted to only Canada and Mexico and no other international stations. 

Pilots may also see the notation on International METAR/TAF: CAVOK.

This means ceiling and visibility OK and is used to replace weather and clouds if visibility is 10 kilometers or more, there are no clouds below 1500 meters (5000 feet) or below the highest minimum air traffic control sector altitude, whichever is greater. Also, there must be no other significant weather. 

NSC means no significant clouds. 

International TAFs may include temperature, turbulence, and icing forecasts.