Explanation of the F6 Preliminary Local Climate Data Report

Each of the columns on the Preliminary Local Climatological Data Report (F6) has a specific meaning. What many of the columns indicate is easy enough to figure out, but there are several that are not so obvious. The following table lists each column by number and abbreviation, and provides a short explanation of what the column represents.

Column Abbreviation Explanation
1 DY The day of the month.
2 MAX The highest temperature observed for the day.
3 MIN The lowest temperature observed for the day.
4 AVG The average temperature for the day. Calculated as the average value of columns 2 and 3, then rounding up if necessary.
5 DEP Departure from normal. Calculated as the difference between the value in column 4 and the 30 year normal temperature for the day.
6a HDD Heating Degree Days. Computed by subtracting column 4 from 65. If column 4 is greater than 65 then HDD is defined as 0.
6b CDD Cooling Degree Days. Computed by subtracting 65 from column 4. If column 4 is less than 65 then CDD is defined as 0.
7 WTR Total precipitation for the day in inches. This value includes all forms of precipitation. Snow or ice is melted before including in this value.
8 SNW Total snowfall for the day in inches.
9 DPTH Snow depth in inches measured at 6:00 AM.
10 AVG SPD Average wind speed for the day in Miles Per Hour.
11 MX SPD The highest wind speed sustained for a 2 minute period in Miles Per Hour.
12 2MIN DIR The direction the wind in column 11 came from, expressed as compass degrees.
  • 360 = North
  • 90 = East
  • 180 = South
  • 270 = West
13 MIN The number of minutes of sunshine received at the station.
14 PSBL The percentage of possible sunshine. Calculated by dividing column 13 by the total possible minutes.
15 S-S The average sky cover between sunrise and sunset, expressed in tenths of the day. For example, a value of 8 means sky cover was observed for approximately 80% of the the daylight hours.
16 WX The weather types observed during the day. Use the following list to decode weather types…
  • 1 = Fog or Mist
  • 2 = Dense Fog (visibility< ¼ mile)
  • 3 = Thunder
  • 4 = Ice Pellets (sleet)
  • 5 = Hail
  • 6 = Glaze or Rime (freezing rain)
  • 7 = Dust Storm or Sand Storm (visibility< ¼ mile)
  • 8 = Smoke or Haze
  • 9 = Blowing Snow
  • X = Tornado
17 SPD Peak wind speed for the day in Miles Per Hour.
18 DR The direction the wind in column 17 came from, expressed as compass degrees.
  • 360 = North
  • 90 = East
  • 180 = South
  • 270 = West

Not all F6 sites have all possible instrumentation, so columns that represent the non-existent instrumentation's readings will be coded with the letter M representing "missing". Precipitation related columns may be coded with the letter T representing "trace".


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.