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Aviation Weather Handbook
United States Department of Transportation
FEDERAL AVIATION ADMINISTRATION
Flight Standards Service
Preface
This handbook is designed as a technical reference for all who operate in the National Airspace System
(NAS).
Pilots, dispatchers, and operators will find this handbook a valuable resource for flight planning
and decision making.
This handbook conforms to pilot weather training and certification concepts established by the Federal
Aviation
Administration (FAA). The discussion and explanations reflect the most commonly used weather
products and information.
It is essential for persons using this handbook to also become familiar with and apply the pertinent parts of
Title 14 of the Code of Federal Regulations (14 CFR) and the Aeronautical Information Manual (AIM).
Title 14 CFR, the AIM, this handbook, current advisory circulars (AC), and other FAA technical references
are available via the internet at the FAA home page at https://www.faa.gov.
This handbook is available for download in Portable Document Format (PDF) from the FAA’s Regulations
and Policies web page at https://www.faa.gov/regulations_policies/handbooks_manuals/aviation.
This handbook was signed and published by the U.S. Department of Transportation (DOT), FAA Aviation
Safety, Flight Standards Service (FS) on April 2, 2026.
The guidance and recommendations in this handbook are not legally binding in their own right and will
not be relied upon by the FAA as a separate basis for affirmative enforcement action or other
administrative penalty. Conformity with the guidance and recommendations is voluntary only and
nonconformity will not affect rights and obligations under existing statutes and regulations.
NOTE: Recently the National Weather Service’s (NWS) Aviation Weather Center’s (AWC) updated their
website (https://aviationweather.gov). There have been numerous and significant changes to that website.
This revision of the Aviation Weather Handbook includes references to that website. To prevent the need
for many updates to this Handbook there are fewer AWC Website images copied from there.
Comments regarding this publication should be sent, in email form, to the following address:
Acknowledgements
This document was prepared under FAA Contract DTFAWA-15-D-00031 with support from AvMet
Applications, Inc.
Individual photographic contributions were made by Blake Spry (front cover), Luke Culver (front cover
and cover of Chapter 15), and Larry Burch (covers of Chapters 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 16, 18,
23, 24, 25, 26, 27, 28, Part 1, Part 2 , and Part 3). Cover of Chapter 20 courtesy of the National Research
Council of Canada.
Notice
The U.S. Government does not endorse products or manufacturers. Trade or manufacturers’ names appear
herein solely because they are considered essential to the objective of this handbook.
Major Revisions
• Updated the Preface.
• Updated references throughout the handbook changing Notices to Air Mission (NOTAM) to Notice
to Airmen (NOTAM).
• In Section 2,
o Added NASA to the Aviation Weather Service Program description
o Added wording on WAFS grids
o Added CERAP to the Section 2.3.3 title
o Added Alaska’s new dedicated phone number information
• In Section 3,
o Added new Section 3.3.3.4
o Changed “GTG” to “GTGN”, Added “GTG” to the Forecast section on Table 3-1
o Added “NDFD” to Table 3-1 and Table 3-2
• In Section 4, added a note on Figure 4-1.
• In Section 5,
o Added “For additional information on how temperature may affect flight performance,
please see Chapter 8” to Section 5.1
o Removed reference to specific heat capacity to Section 5.7
o Removed “capacity” from the name and column heading on Table 5-4
o Removed “capacity” from the two paragraphs at the bottom of page 5-9
o Adjusted wording in Section 5.7 (first paragraph) to improve accuracy
• In Section 15, added a new section on chaff and figure showing radar image of chaff.
• In Section 16, added an enhancement to Figure 16-6 for clarity.
• In Section 19, added wording for clarity in Section 19.2.2.
• In Section 20,
o Changed SLD minimum size to 50 microns
o Deleted a reference to altitude in Section 20.4.1
o Replaced wording in Section 20.4.1 for clarity
• In Section 22, added “Do not” to the front of #7.
• In Section 23,
o Reworded Section 23.1’s introduction for clarity
o Updated language on our understanding of the physics of sunspots
o Updated language around magnetic fields
o Updated the range of frequencies of solar electromagnetic emissions
o Added a definition of corona
o Refined the description of the cause of an aurora
o Changes percentage of GCR flux for consistency with recent publications
• In Section 24,
o Due to changes on the AWC website, language was updated and multiple figures were
deleted
o Changed “sm” to “SM” in several locations.
o Deleted “, or Dust/Sand Whirl (Dust Devil)” from the first column in Table 24-2
o Added a note in Section 24.4.3.7 saying “Note: The link to the RVR website is locate d in
Appendix G.”
o Deleted Section 24.6.1.5 and Figure 24-18, both are no longer used
o Updated Section 24.9.1 provided the new Weather Camera Program information
• In Section 25,
o Added Analyzed Weather to the Introduction
o Removed reference to the AWC website
o Changed Figure 25-3 and 25-16
o Deleted graphic references no longer available
o Deleted Figures 25-25, 25-26, and 25-27
o Enhanced the description of the weather products that are used to generate CIP 2 changes
o Deleted “icing” from “AWC’s icing website”
o Changed Section 25.6’s title for clarity
o Corrected Section references in Section 25.5
• In Section 26, deleted Figure 26-8 and all references to the figure.
• In Section 27,
o Deleted references to the AWC GFA Tool
o Deleted Figures 27-1, 27-2, 27-33, 27-34, 27-35
o Deleted Section 27.12.3 and 27.12.4, sections renumbered
o Removed missing reference information from end of Section 27.12.3 sentence
o Deleted sentence referencing the AWC website
o Changed the typo at the end of Section 27.2.1.1.2 (4th line) under “Sample winds aloft text
message” and top of next page from 550252 to 750252
o Updated PROB 30 wording to reflect NWS changes
o Added language around the use of temperature information from the LAMP/MOS product
o Added text “The NWS will continue producing text FAs for Alaska for the foreseeable
future”
o Added language for clarity, deleted PIREPs from FIP sourcing, and removed bullets
referencing CIP and FIP
o Added language around use of the LAMP product for destination forecast planning
o Removed “Implementation of additional levels are planned in 2024” and specific location
in AWC website
o Removed references to FAs for Hawaii, Gulf of America, and the Caribbean
o Deleted Sections 27.6.4.2, 27.6.4.3, and 27.6.4.3
o Changed definition of heavy ice to Section 27.12
o Removed reference to CIP from Section 27.12
• In Section 28,
o Deleted Figure 28-1 (and references to the figure), Figure 28-2, and Section 28.4
o Changed the HEMS Tool to Graphical Forecast for Aviation (Low Altitude, GFA-LA)
o Added language in Section 28.2 regarding the change from HEMS to GFA-LA
• In Appendices,
o Appendix D: Added a reference to RVR in Table D-1