noaa-ghcn-dataset/s3://noaa-ghcn-pds

The "station".csv files contain all daily elements for that GHCN station for its entire period of record. 
Each element-day is provided on a separate line and all files are updated daily for the entire period of record.

The following information serves as a definition of each field for all element-day records. 
Each field described below is separated by a comma ( , ) and follows the order below:

ID = 11 character station identification code
YEAR/MONTH/DAY = 8 character date in YYYYMMDD format (e.g. 19860529 = May 29, 1986)
ELEMENT = 4 character indicator of element type 
DATA VALUE = 5 character data value for ELEMENT 
M-FLAG = 1 character Measurement Flag 
Q-FLAG = 1 character Quality Flag 
S-FLAG = 1 character Source Flag 
OBS-TIME = 4-character time of observation in hour-minute format (i.e. 0700 =7:00 am); if no ob time information 
is available, the field is left empty

See section III of the GHCN-Daily readme.txt file (ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/readme.txt)
for an explanation of ELEMENT codes and their units as well as the M-FLAG, Q-FLAG and S-FLAG.

The OBS-TIME field is populated with the observation times contained in NOAA/NCEI's HOMR station history database.