Lets look at a sample TAF report:

KIAH 020525Z 020606 04004KT P6SM SKC
  FM1200 07005KT P6SM SCT020
FM1500 10007KT P6SM BKN020
FM1700 13008KT P6SM BKN020
FM2000 14011KT P6SM BKN020
FM0300 15009KT P6SM BKN015
1 Type of Report A TAF can be either a routine forecast (TAF) or an amended forecast (TAF AMD). 6 Forecast Visibility The forecast visibility is given in statute miles and may be in whole numbers or fractions. If the forecast is greater than 6 miles, it will be coded as “P6SM.”
2 ICAO Station Identifier The station identifier is the same as that used in a METAR. 7 Forecast Significant Weather Weather phenomenon is coded in the TAF reports in the same format as the METAR. If no significant weather is expected during the forecast time period, the denotation “NSW” will be included in the “becoming” or “temporary” weather groups.
3 Date and Time of Origin Time and date of TAF origination is given in the six-number code with the first two being the date, the last four being the time. Time is always given in UTC as denoted by the Z following the number group. 8 Forecast Sky Condition Forecast sky conditions are given in the same manner as the METAR. Only cumulonimbus (CB) clouds are forecast in this portion of the TAF report as opposed to CBs and towering cumulus in the METAR.
4 Valid Period Date and Time The valid forecast time period is given by a six-digit number group. The first two numbers indicate the date, followed by the two-digit beginning time for the valid period, and the last two digits are the ending time. 9 Forecast Change Group For any significant weather change forecast to occur during the TAF time period, the expected conditions and time period are included in this group. This information may be shown as From (FM), Becoming (BECMG), and Temporary (TEMPO). “From” is used when a rapid and significant change, usually within an hour, is expected. “Becoming” is used when a gradual change in the weather is expected over a period of no more than 2 hours. “Temporary” is used for temporary fluctuations of weather, expected to last for less than an hour.
5 Forecast Wind The wind direction and speed forecast are given in a five-digit number group. The first three indicate the direction of the wind in reference to true north. The last two digits state the windspeed in knots as denoted by the letters “KT.” Like the METAR, winds greater than 99 knots are given in three digits. 10 Probability Forecast The probability forecast is given percentage that describes the probability of thunderstorms and precipitation occurring in the coming hours. This forecast is not used for the first 6 hours of the 24-hour forecast.

Source: Pilot's Handbook of Aeronautical Knowledge