What are the key considerations when designing a weather application to be fully accessible to visually impaired users, adhering to WCAG standards?

When designing a weather application to be fully accessible to visually impaired users and adhering to WCAG (Web Content Accessibility Guidelines) standards, several key considerations are paramount, primarily semantic HTML, ARIA attributes, sufficient color contrast, keyboard navigation, and alternative text for images. 'WCAG' are a set of international guidelines for making web content more accessible to people with disabilities. 'Semantic HTML' refers to using HTML elements according to their intended meaning, such as using '<header>' for headers, '<nav>' for navigation, and '<article>' for articles. This helps screen readers understand the structure of the page. 'ARIA attributes' (Accessible Rich Internet Applications) are HTML attributes that provide additional information to assistive technologies, such as screen readers, about the role, state, and properties of elements. 'Color contrast' refers to the difference in luminance between the foreground and background colors. Sufficient color contrast is essential for users with low vision. 'Keyboard navigation' means that all interactive elements on the page can be accessed and operated using the keyboard. 'Alternative text' (alt text) is a short description of an image that is displayed when the image cannot be loaded or when a screen reader is used. For a weather application, using semantic HTML would involve using appropriate tags to mark up the different sections of the page, such as the current conditions, the forecast, and the radar map. ARIA attributes could be used to provide additional information about interactive elements, such as the city search box or the temperature units selector. Ensuring sufficient color contrast would involve choosing foreground and background colors that are easy to distinguish for users with low vision. Implementing keyboard navigation would involve making sure that all interactive elements can be accessed using the tab key and operated using the enter or space key. Providing alternative text for images would involve adding descriptive alt text to all images, such as the weather icons or the radar map. For example, the alt text for a sun icon could be 'Sunny weather'. Furthermore, ensuring that dynamic content updates are announced to screen readers is critical. When new weather data is loaded, the application should use ARIA live regions to notify screen reader users of the changes. This ensures they are aware of the most current information. Addressing these considerations will enable visually impaired users to access and use the weather application effectively.