I know that METAR data are available at hourly intervals from the US National Oceanic and Atmospheric Administration (see e.g. the report for Karpathos Airport, Greece ). However, I would have thought that at the age of the internet it would have been possible to obtain (near) real-time data regarding an airport's weather. Is such a service available? Is there a better (more frequently updated) internet-accessible source for global METAR data than NOAA?
Although METARs don't provide real-time weather, you can programmatically obtain the current METAR using the ADDS Text Data Server
Here's a sample result for KDEN:
KDEN 061653Z 31004KT 10SM BKN025 OVC120 22/14 A3014 RMK AO2 SLP134 T02220144,KDEN,2016-08-06T16:53:00Z,39.85,-104.65,22.2,14.4,310,4,,10.0,30.138779,1013.4,,,TRUE,,,,,,,BKN,2500,OVC,12000,,,,,MVFR,,,,,,,,,,,,METAR,1640.0