Preliminary 2026 Edition of the Guide to Instruments and Methods of Observation (WMO-No. 8)

Updates to WMO-No. 8

The Preliminary 2026 edition of the Guide to Instruments and Methods of Observation (WMO-No. 8) (Volumes I, II, III, V and VI) is now available for consideration by Members.

This edition has been developed through the collaborative efforts of the different expert teams and relevant groups, together  with the INFCOM Standing Committee on Measurements, Instrumentation and Traceability (SC-MINT). The updated and new chapters/volume are now available for Members' review and feedback prior to finalization. 

The preliminary 2026 edition of WMO-No. 8 includes updates of Chapters 1, 4, 6 and 13 of Volume I, Chapter 2 of Volume II, Chapters 2, 4, 5 and 8 of Volume III, Chapters 1 and 5 of Volume V. It also includes a new Chapter 5 of Volume II. A new volume for Measurement of Marine Meteorological and Oceanographic Variables has also been developed as Volume VI for 2026 edition. 

You are invited to examine the chapters available from the table below and send your detailed comments or suggestions to the WMO Secretariat, to the attention of Mr Ercan Buyukbas at: ebuyukbaswmo [dot] int (ebuyukbas[at]wmo[dot]int), preferably through the Permanent Representative of your country with WMO. Please submit your comments at your earliest convenience, but not later than 15 August 2026, by downloading and filling out the comment template accessible here. Your valuable feedback will be considered for the development of the Provisional 2026 edition that will be submitted to the upcoming fourth session of the Commission for Observation, Infrastructure and Information Systems (INFCOM-4) for approval. 

Note 1: Each chapter proposed to be updated is available in two versions. The "track-change" (...tc) version shows all the changes made to the 2024 edition of Volumes I, II and III, and 2023 edition of Volume V visible in track-change mode. In the "clean" (...clean) version files all those changes have already been accepted. The new chapter (Chapter 5 of Volume II), mostly rewritten chapter (Chapter 2 of Volume II) and chapters of new volume (Volume VI) are available only in "clean" version. An overview of the size of the proposed updates is available here. 

Note 2: The missing figures and tables in this preliminary edition will remain the same as they are in the 2024 edition and will be inserted before publication. To check them, please visit the most recent version of the WMO-No. 8, reachable here. Also, the formatting of the documents will be finalized at the time of publication of the new edition.

Note 3: For the chapters not listed below, changes have not been proposed and the chapters will remain the same as in 2024 edition of Volumes I, II and III, and 2023 edition of Volume V.