a. TYPE OF REPORTS - the METAR, and the SPECI (aviation special weather report)
b. ICAO station identifier - 4-letter station identifiers; in the contiguous US, the 3-letter identifier is prefixed with K.
c. DATE AND TIME OF REPORT - a 6-digit date/time gropu appended with Z (UTC). First two digits are the date, then two for the hour, and two for minutes.
d. MODIFIER (as required) - if used, the modifier AUTO identifies the report as an automated weather report with no human intervention. If AUTO is shown in the body of the report, AO1 or AO2 will be encoded in the remarks section to indicate the type of precipitation sensor used at the station.
e. WIND - 5-digit group (6 digits if speed is over 99 KTS); first three digits = wind direction, in tens of degrees referenced to true north. Directions less than 100 degrees are preceded with a zero; next two digits are the average speed in knots, measured or estimated (or, if over 99 KTS, the next three digits).
f. VISIBILITY - surface visibility in statute miles, space, fractions of statute miles (as needed), and the letters SM.
g. RUNWAY VISUAL RANGE (RVR), as required
h. WEATHER PHENOMENA - broken into two categories: qualifiers and weather phenomena.
i. SKY CONDITION - amount/height/type (as required) or indefinite ceiling/height (vertical visibility). Heights are recorded in feet AGL.
j. TEMPERATURE/DEW POINT GROUP - 2 digit format in whole degrees Celsius, separated by a solidus (/). Temperatures below zero are prefixed with M.
k. ALTIMETER - 4-digit format representing tens, units, tenths, and hundredths of inches of mercury prefixed with A. The decimal point is not reported or stated.
l. REMARKS (RMK), as required - operational significant weather phenomena, location of phenomena, beginning and ending times, direction of movement.