USHCN daily data are available as ASCII files. 
The format of each record in an ASCII data file, be it a state-level 
file (e.g., state01_AL.txt) or the file for the entire U.S. (us.txt) 
is as follows. (Each record in a file contains one month of daily data.)

Variable 	  	Columns 	  	Type
COOP ID 	  	1-6 	  	Character
YEAR	 	  	7-10 	  	Integer
MONTH 		  	11-12 	  	Integer
ELEMENT 	  	13-16 	  	Character
VALUE1 		  	17-21 	  	Integer
MFLAG1 		  	22 	  	Character
QFLAG1 		  	23 	  	Character
SFLAG1 		  	24 	  	Character
VALUE2 		  	25-29 	  	Integer
MFLAG2 		  	30 	  	Character
QFLAG2 		  	31 	  	Character
SFLAG2 		  	32 	  	Character
. 	  	. 	  	.
. 	  	. 	  	.
. 	  	. 	  	.
. 	  	. 	  	.
VALUE31 	  	257-261 	Integer
MFLAG31 	  	262 	  	Character
QFLAG31 	  	263 	  	Character
SFLAG31 	  	264 	  	Character

These variables have the following definitions:

COOP ID 	is the U.S. Cooperative Observer Network station identification
		code. Note that the first two digits in the Coop Id correspond to the state.
  	  	 
YEAR 	  	is the year of the record.
  	  	 
MONTH 	  	is the month of the record.
  	  	 
ELEMENT   	is the element type. There are five possible values:
  	  	PRCP = precipitation (hundredths of inches)
  	  	SNOW = snowfall (tenths of inches)
  	  	SNWD = snow depth (inches)
  	  	TMAX = maximum temperature (degrees F)
  	  	TMIN = minimum temperature (degrees F)

VALUE1 	  	is the value on the first day of the month (missing = -9999).
  	  	 
MFLAG1 	  	is the measurement flag for the first day of the month. There are five possible values:
  	  	Blank = no measurement information applicable
  	  	B = precipitation total formed from two 12-hour totals
  	  	D = precipitation total formed from four six-hour totals
  	  	L = temperature appears to be lagged with respect to reported hour of observation
  	  	T = trace of precipitation, snowfall, or snow depth
  	  	 
QFLAG1 	  	is the quality flag for the first day of the month. There are fourteen possible values:
  	  	Blank = did not fail any quality assurance check
  	  	A = failed accumulation total check
  	  	D = failed duplicate check
  	  	G = failed gap check
  	  	I = failed internal consistency check
  	  	K = failed streak/frequent-value check
  	  	M = failed megaconsistency check
  	  	N = failed naught check
  	  	O = failed climatological outlier check
  	  	R = failed lagged range check
  	  	S = failed spatial consistency check
  	  	T = failed temporal consistency check
  	  	W = temperature too warm for snow
  	  	X = failed bounds check

SFLAG1          is the source flag for the first day of the month.  There are 
                sixteen possible values (including blank):

                Blank = No source (i.e., data value missing)
                0     = U.S. Cooperative Summary of the Day (NCDC DSI-3200)
                1     = U.S. Preliminary Cooperative Summary of the 
                        Day -- Transmitted 
                2     = U.S. Preliminary Cooperative Summary of the 
                        Day -- Keyed from paper forms
                6     = CDMP Cooperative Summary of the Day (NCDC DSI-3206)
                A     = U.S. Automated Surface Observing System (ASOS) 
                        real-time data (since January 1, 2006)
                B     = U.S. ASOS data for October 2000-December 2005 (NCDC 
                        DSI-3211)
                F     = U.S. Fort data 
                G     = Official Global Climate Observing System (GCOS) or 
                        other government-supplied data
                H     = High Plains Regional Climate Center real-time data
                I     = International collection (non U.S. data received through
	                personal contacts)
                M     = Monthly METAR Extract (additional ASOS data)
	        Q     = Data from several African countries that had been 
	                "quarantined", that is, withheld from public release
		        until permission was granted from the respective 
	                meteorological services
                R     = NCDC Reference Network Database (Climate Reference Network
	                and Historical Climatology Network-Modernized)
                S     = Global Summary of the Day (NCDC DSI-9618)
                        NOTE: "S" values are derived from hourly synoptic reports
                        exchanged on the Global Telecommunications System (GTS).
                        Daily values derived in this fashion may differ
                        significantly from "true" daily data, particularly for precipitation
                        (i.e., use with caution).
                X     = U.S. First-Order Summary of the Day (NCDC DSI-3210)

VALUE2          is the value on the second day of the month

MFLAG2          is the measurement flag for the second day of the month.

QFLAG2          is the quality flag for the second day of the month.

SFLAG2          is the source flag for the second day of the month.

... and so on through the 31st day of the month.  Note: If the month has less 
than 31 days, then the remaining variables are set to missing (e.g., for
April, VALUE31 = -9999, MFLAG31 = blank, QFLAG31 = blank, SFLAG31 = blank).