This booklet is a simple guide to the aeronautical meteorological codes, METAR, SPECI and TAF, applicable on 4 November 2021, updated as a result of the alignment of the Technical Regulations (WMO-No. 49), Volume II – Meteorological Service for International Air Navigation, Parts I and II, with Amendment 80 to Annex 3 to the Convention on International Civil Aviation. It is aimed at a wide range of users such as pilots, flight dispatchers, air traffic control staff and meteorological observers at smaller aerodromes where sophisticated automated instruments are not available. Although the readers of this handbook may not be professional meteorologists, it is assumed that they have some formal meteorological training.