Each data column in a fixed-width table contains a specific, predefined number of characters—and always that number of characters. This means that the meaningful data in fixed-width files are often padded with extra characters, such as spaces or zeroes.

ghcnd-station.txt

ACW00011604  17.1167  -61.7833   10.1    ST JOHNS COOLIDGE FLD
ACW00011647  17.1333  -61.7833   19.2    ST JOHNS
AE000041196  25.3330   55.5170   34.0    SHARJAH INTER. AIRP            GSN     41196
AEM00041194  25.2550   55.3640   10.4    DUBAI INTL                             41194
AEM00041217  24.4330   54.6510   26.8    ABU DHABI INTL                         41217
AEM00041218  24.2620   55.6090  264.9    AL AIN INTL                            41218
AF000040930  35.3170   69.0170 3366.0    NORTH-SALANG                   GSN     40930
AFM00040938  34.2100   62.2280  977.2    HERAT                                  40938
AFM00040948  34.5660   69.2120 1791.3    KABUL INTL                             40948
AFM00040990  31.5000   65.8500 1010.0    KANDAHAR AIRPORT                       40990
AG000060390  36.7167    3.2500   24.0    ALGER-DAR EL BEIDA             GSN     60390
AG000060590  30.5667    2.8667  397.0    EL-GOLEA                       GSN     60590
AG000060611  28.0500    9.6331  561.0    IN-AMENAS                      GSN     60611
AG000060680  22.8000    5.4331 1362.0    TAMANRASSET                    GSN     60680
AGE00135039  35.7297    0.6500   50.0    ORAN-HOPITAL MILITAIRE
AGE00147704  36.9700    7.7900  161.0    ANNABA-CAP DE GARDE
AGE00147705  36.7800    3.0700   59.0    ALGIERS-VILLE/UNIVERSITE
AGE00147706  36.8000    3.0300  344.0    ALGIERS-BOUZAREAH
AGE00147707  36.8000    3.0400   38.0    ALGIERS-CAP CAXINE
AGE00147708  36.7200    4.0500  222.0    TIZI OUZOU                             60395
AGE00147709  36.6300    4.2000  942.0    FORT NATIONAL
AGE00147710  36.7500    5.1000    9.0    BEJAIA-BOUGIE (PORT)                   60401

Example of a fixed-width data file

It is pretty clear that each column represents some kind of data. However, to precisely identify the delimiter is quite challenging without metadata, you can guess and try until you figure it out.

With metadata:

III. FORMAT OF DATA FILES (".dly" FILES)

Each ".dly" file contains data for one station.  The name of the file
corresponds to a station's identification code.  For example, "USC00026481.dly"
contains the data for the station with the identification code USC00026481).

Each record in a file contains one month of daily data.  The variables on each
line include the following:

------------------------------
Variable   Columns   Type
------------------------------
ID            1-11   Character
YEAR         12-15   Integer
MONTH        16-17   Integer
ELEMENT      18-21   Character
VALUE1       22-26   Integer
MFLAG1       27-27   Character
QFLAG1       28-28   Character
SFLAG1       29-29   Character
VALUE2       30-34   Integer
MFLAG2       35-35   Character
QFLAG2       36-36   Character
SFLAG2       37-37   Character
  .           .          .
  .           .          .
  .           .          .
VALUE31    262-266   Integer
MFLAG31    267-267   Character
QFLAG31    268-268   Character
SFLAG31    269-269   Character
------------------------------

This is followed by a detailed description of what each field contains or means, including information like units.