MANOBS Manual of Surface Weather Observations

cover of publication

Eighth Edition

Originating Authority:
Monitoring and Data Services Directorate
Issued under the authority of the Assistant Deputy Minister
Meteorological Service of Canada

Crown Copyrights Reserved

Effective: February 2019

Available Formats:
HTML (summary of chapters)
PDF: 3.7 MB (full version available through

Author: Environment and Climate Change Canada

Language of Document: Separate English/French

Document Type: Manual

ISBN: 978-0-660-27957-2

Catalog Number: En56-238/2-2018E-PDF

Size: 21.6 cm X 28 cm

Pages: 187

Year: 2019

Summary of the Eighth Edition


The Manual of Surface Weather Observations Standards (MANOBS), Eighth Edition, has been prepared with due consideration to the recommended standards set down by the World Meteorological Organization (WMO) and, for the aeronautical portions, by the International Civil Aviation Organization (ICAO) and Canadian Aviation Regulations (CARs). The standards set out in MANOBS do not inhibit agencies from doing more than is specified.

Manual conventions

Throughout this manual:

  • The term “shall” or “shall not” indicates that compliance with a standard is mandatory
  • All references to miles (mi.) are references to the international statute mile (precisely equal to 1.609344 km)
  • All reference for clouds based height are in feet (precisely equal to 0.3048 meters)
  • All reference for wind speed are in knots (precisely equal to 1.852 km/h)

The following typographical and stylistic conventions are used throughout this manual:

  • Code forms, symbolic letters and code figures have been printed in 14 point dark blue Courier New font
  • Notes have been printed in medium grey-shaded boxes, preceded by the word “Note” in bold
  • Blank table cells have been marked with an en-dash “–” to indicate to assistive technology users that these cells may be ignored


Amendments will be issued when warranted, and a review will take place in conjunction with amendments to relevant WMO and ICAO standards. All holders of the manual are responsible for keeping their copies current. When amendments are entered in the manual, they should be recorded on the page headed “Record of amendments.” 

The version of the Manual found published on the Meteorological Service of Canada website, in either official language, shall be considered to be the official version. 

Changes, additions, deletions, and corrections will be issued as necessary solely by the Meteorological Service of Canada after consultation and coordination with the working group responsible for MANOBS.


Inquiries about the content of this manual should be directed to the Assistant Deputy Minister (ADM), Meteorological Service of Canada, through appropriate channels. 


MANOBS is applicable to stations taking the following types of observations:

  • Staffed: Stations where certified surface weather observers are responsible for the meteorological observations
  • Automated: Stations where surface weather observing systems are implemented to prepare the requisite meteorological reports for transmission, without a certified weather observer being present

Observing procedures

With the publication of the Eighth Edition, procedures and practices specific to weather observing have been removed from MANOBS. Individual service providers shall issue their own manuals setting out their weather observing procedures and practices which implement the MANOBS standards. Such manuals shall complement, not supersede, the standards contained in MANOBS, Eighth Edition.

Pilot reports (PIREPS)

Pilot reports are no longer part of MANOBS. The responsibility for publishing procedures for PIREPS now resides with individual service providers (NAV CANADA and Department of National Defence). 

Editor's remarks

This manual has been edited to be consistent with the Government of Canada’s brand guidelines, and best practices for accessibility (Web Content Accessibility Guidelines 2.0), as well as the design and structural requirements of the Content Style Guide.


Part A Standards for weather observing programs

Chapter 1 Introduction

This chapter contains information on the legal authority for meteorological and aeronautical matters, as well as the application of that authority as set out in MANOBS and related publications. Information on the World Meteorological Organization and synoptic reports is also provided.

Chapter 2 Surface weather observing program standards

The purpose of routine aeronautical weather observations is to provide detailed information on current weather for aviation and aviation forecasting. Records of weather observations have both immediate and long-term value. Information obtained from aeronautical weather observations is also used for public forecasts, building codes, climatological data and other weather related purposes. 

A surface weather observation is an evaluation of meteorological elements, visually and by measurement at a specified location on the earth's surface (usually an aviation weather observing station). 

This chapter is meant to introduce aviation weather observing program staff to the general standards and requirements of weather observing programs. This chapter contains information on sensor siting, types of staffed and automated observations, reference points for observations, standard parameters to be observed, and times and schedules of observations.

Chapter 3 Wind standards

This chapter describes the wind information that is required to be contained in a METAR/SPECI and the standards for the instrument that measured the winds. Standards for wind characteristics such as calm wind, gusts, squalls, wind shift, variable wind direction, variations in wind direction and estimation of wind are given. Tables for estimating wind and examples of surface weather reports are also given.

Chapter 4 Visibility standards

This chapter defines visibility and describes the standards for reporting visibility, including the standards related to the unit of measure, variable visibility and identification of the elevated position. Descriptions of prevailing visibility, point of observation and visibility charts are given. Examples of visibility remarks are also provided.

Chapter 5 Runway visual range (RVR)

This chapter details standards for reporting RVR and provides examples of RVR remarks used in surface weather reports.

Chapter 6 Atmospheric phenomena standards

This chapter defines present weather and describes the standards for reporting atmospheric phenomena, determining intensity and character, and for observing miscellaneous phenomena and unusual weather conditions. This chapter is structured to provide a definition, standards for reporting, and examples of remarks for each of the following present weather phenomena: tornadoes, waterspouts, funnel clouds, thunderstorms, lightning, precipitation, and obstructions to vision.

Chapter 7 Sky condition standards

This chapter describes the standards for reporting sky conditions and the definition of cloud types. Terms and definitions are given for celestial dome, sky condition, obscuring layers, total amount, and reference level. Sky condition standards are given for cloud amount, vertical visibility, and variable ceiling, followed by examples of remarks. Abbreviations of cloud types and obscuring phenomena for use in reporting sky conditions are also provided.

Chapter 8 Air and dew-point temperature

This chapter provides definitions of terms and describes the standards for air and dew-point temperature. 

The temperature of a body is the condition which determines its ability to communicate heat to other bodies or to receive heat from them. In a system of two bodies, the one that loses heat to the other is said to be at the higher temperature. With the latest technologies, the temperature is now derived from automated instruments which already have corrections and tolerances built into them.

Chapter 9 Atmospheric pressure standards

This chapter first defines station elevation and the units of measurements used for atmospheric pressure, and then the standards for observing and reporting atmospheric pressure are described.

Chapter 10 General aviation remarks

This chapter explains what general aviation remarks are and outlines the standards for their usage. Criteria for inclusion of remarks and supplementary meteorological information are also provided.

Chapter 11 METAR—Aerodrome routine meteorological report

METAR (Aerodrome routine meteorological report) is the primary observation code reported on the hour (UTC) when reporting surface meteorological data. SPECI (Aerodrome special meteorological report) is an unscheduled report taken when any of the selected changes in weather conditions significant to aviation occur off the hour (UTC). LWIS (Limited Weather Information System) is a system that generates additional weather reports outside the hours of human observations. 

This chapter describes standards for coding and reporting METAR, SPECI, and LWIS reports. It provides the symbolic code forms of each type of report, followed by detailed descriptions of the code groups and elements that make up a particular code form. Guidance and notes to ensure standard encoding of observed meteorological data are also included.

Chapter 12 Automatic system standards

This chapter explains what an automated observing and reporting system is and outlines the standards for observations, reports, and instruments when using an automated system. Examples of remarks to be used for weather elements are provided. This chapter applies to service providers who provide aviation weather services consisting of automated observation and reporting of any or all of the following: wind direction, speed and character; visibility, RVR, present weather, sky condition, temperature, dew-point temperature, atmospheric pressure and remarks.

Chapter 13 Glossary of Terms

This chapter provides definitions of terms used in this manual.


Part B Standards for synoptic observations and reports

Chapter 14 The synoptic code—general description

This chapter provides a general description of the international meteorological code FM 12-XIV Ext. SYNOP. The symbolic form of the synoptic code is given, followed by general operational details for reporting synoptic surface weather observations from land stations. 

Chapter 15 The synoptic code—detailed description

This chapter provides a detailed description of the international meteorological code FM 12-XIV Ext. SYNOP. A description and the symbolic form of sections 0, 1, 3, and 5 of the synoptic code are provided, followed by section content. Within each section’s code group, a detailed interpretation of all particular symbols is given. Detailed descriptions of Section 2 and Section 4 of the synoptic code are both omitted as these sections are, respectively, not used by surface weather stations and not used within Canada.



Appendix 1 Stations where SPECI reports are required for temperature changes

This appendix contains a list of NAV CANADA designated sites that are required to issue special (SPECI) reports when temperature changes occur.

Appendix 2 METAR Weather Phenomena

This appendix contains a quick reference table for encoding weather phenomena in METAR.


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