watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 5 (40mm, LTE), released on 2026-02-02T18:44:49Z. The update package is 674.83 MB. This is a delta (partial) update that requires 6.0 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 5b4a7a8d6048aecba4e6e40aa58754523e3c0321.zip.