U.S. Airports (accepts ICAO/FAA/IATA codes)
http://www.airnav.com/airports/
CWOP (accepts ICAO/SYNOP/CMAN/BUOY codes)
https://weather.gladstonefamily.net/cgi-bin/wxsite.pl?&Get+information=Get+information
Great Circle (accepts ICAO/FAA/IATA codes)
http://gc.kls2.com/cgi-bin/gclookup
Canada AUTO sites not sent in METAR format (XML format, scroll down to
"latest")
https://dd.weather.gc.ca/observations/swob-ml/
NCEP METAR Station List (not all listed send METARs)
https://www.nco.ncep.noaa.gov/pmb/codes/nwprod/decoders/decod_shared/dictionaries/metar.tbl
NDBC (for CMAN/BUOY/other marine sites)
https://www.ndbc.noaa.gov/
NDBC list of active marine stations (XML format)
https://www.ndbc.noaa.gov/activestations.xml
Gulf of Mexico platform AWOS (search for "AWOS")
http://hsac.org/library
WMO OSCAR/SURFACE (SYNOPs)
https://oscar.wmo.int/surface/#/
WMO Pub. 9, Vol. A legacy format (SYNOPs)
https://oscar.wmo.int/oscar/vola/vola_legacy_report.txt
Boris
