Audit Summary - February 2026

This audit was carried out by CACI Ltd. on behalf of the Met Office. The testing included a manual audit of a representative sample of pages and components, supported by automated testing tools and assistive technologies.

The audit identified 113 distinct accessibility barriers across the site pages and components affecting 30 different criteria.

The current MAVIS application contains a large number of accessibility barriers across critical user journeys, particularly on the Map, Report Viewer, Weather Thresholds, and Settings areas. These issues prevent equal access for screen reader users, keyboard only users, users with low vision, and users with cognitive impairments. Several failures relate to fundamental architectural patterns that require structural redesign rather than small fixes.

The most significant risks are concentrated around perception of weather information, map interaction, report accessibility, and keyboard navigation.

Key Findings by Severity

Critical

• Canvas based report viewer is inaccessible, providing no text alternative or structural information.
• Weather map overlays and legends have no accessible alternative, leaving core meteorological content unusable for assistive technology.
• Map marker design fails multiple WCAG criteria, including name/role/value, keyboard operability, focus visibility, and use of colour.
• Hamburger menu and site-wide navigation are not keyboard accessible, focus routinely becomes “lost” off screen.
• Focus indicators missing or suppressed, making navigation impossible for keyboard-only users.
• Timeline control changes not announced, leaving screen reader users unaware of updates.
• Incorrect or missing ARIA labels on key controls, including map controls, drawers, sidebars, and settings.
• RAG system uses colour as primary indicator, with inadequate non-colour alternatives.
• Important status banners are not surfaced to assistive technology, leading to misunderstanding of threshold applicability.
• Modals lack proper focus trapping, allowing users to tab into hidden page elements.

High

• Major contrast failures across text elements, badges, and buttons.
• Non-semantic structure in lists, tables, and headings.
• Illogical tab order across navigation, sidebars, reports, and settings.
• External links behave inconsistently and do not warn users of context changes.
• Keyboard access missing for map display settings, weather threshold selection, and sidebar elements.
• Table-based forecast data is not keyboard navigable for non-screen-reader users.

Medium

• Insufficient or generic alt text for instructional images and map snippets.
• Decorative icons not marked as such, causing unnecessary verbosity for screen reader users.
• Headings misused for styling, creating confusing content hierarchy.
• Inconsistent page titles and labels, increasing user confusion.

Thematic Areas of concern

Structural issues

• Several issues stem from HTML structure that does not support accessibility:
• Overuse of div elements based custom widgets instead of semantic elements
• Hidden but still focusable elements
• Incorrect use of ARIA attributes or typos
• Landmark regions missing or misused
• These require pattern-level redesign, not incremental patching.

Inaccessible Weather content

Weather information — the central purpose of MAVIS — is delivered as:

• Canvas-rendered PDFs
• Image-based overlays
• Colour-coded graphics without text equivalents

There is no programmatic access to the underlying data, making weather analysis impossible for users relying on assistive technology.

Keyboard and Screen reader navigation

Site-wide navigation has systemic accessibility failures:

• Hamburger menu traps focus or loses it entirely
• Menu items remain in tab order when visually hidden
• Navigation structure inconsistent across pages
• Missing skip links

This results in severe barriers for keyboard and screen reader users.

Many core controls are not operable via keyboard:

• Map markers
• Weather thresholds
• Map display settings
• Report validity filters
• Sidebar tabs
• Timeline controls

Inconsistent use of colour labels and instructions

The RAG system, map markers, and report indicators rely on colour alone and labels often lack descriptive meaning. Instructional context is frequently missing.

High Level Recommendations

Redesign core components

Focus on systemic fixes rather than incremental workarounds.

• Replace Canvas report viewer with accessible HTML or fully tagged accessible PDFs.
• Ensure equal access without requiring external apps
• Provide text based alternatives for all map layers ()
• Make legends programmatically descriptive
• Announce weather changes triggered by the timeline
• Rebuild map markers using a single button element per marker and ensure visible focus states
• Provide full accessible names (code, site name, status)
• Ensure visible focus states and keyboard operability for all markers and controls
• Add keyboard navigation alternatives such as search, and list view
• Rebuild site navigation ensuring hidden items are not focusable and removed from the tab order.
• Add skip links and ensure logical tab order across the site
• Add escape to close patterns for modals and drawers Manage focus correctly when opening and closing to prevent loss of context.

Fix Key Interaction Patterns

• Make all sliders, toggles, radio groups and tabs fully keyboard operable.
• Add proper focus trapping to modals and drawers.
• Ensure headings and landmarks are used correctly.
• Correct ARIA labels and add them where missing.
• Provide structural fixes for tables, lists and headings.

Improve Colour Contrast Across The App

• Address all contrast failures to meet WCAG AA (4.5:1).
• Add non-colour indicators to the RAG status markers and legend items.
• Underline in line links consistently.

Enhance User Guidance

• Improve alt text quality.
• Add clear instructions in weather thresholds.
• Add psychological safety messaging in modals and warnings.
• Ensure external links are clearly labeled and warn users of context changes.

Strategic Recommendations

1. Stabilise the core application (High Impact / Short term)

   • Navigation and focus issues
   • Add missing labels to critical controls
   • Improve link styling and colour contrast
   • Correct modal focus trapping
   • Add skip links and ensure logical tab order

2. structural remediation

   • rebuild map marker pattern
   • Fix sidebar / tab patterns
   • Correct heading hierarchy across pages
   • Implement robust keyboard navigation

3. Accessible Weather Delivery

   • Replace canvas viewer
   • Provide accessible equivalents for weather overlays
   • Implement data tables and summaries for map layers
   • Add timeline status messaging

4. Experience Improvements

   • Provide comprehensive instructions for thresholds
   • Enhance on boarding and tutorials
   • Improve consistency across pages

Executive Conclusion

MAVIS contains a substantial number of accessibility failures across almost every core feature. Many are core to the page design and layout. Remediation will require pattern-level redesign rather than incremental fixes. Addressing the critical failures, particularly around the map, timeline reports and navigation is essential to ensure MAVIS meets WCAG standards and provides equal access to all users.