watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 5 (44mm, LTE), released on 2026-02-02T18:44:52Z. The update package is 543.24 MB. This is a delta (partial) update that requires 6.1.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 81b633301f4bf710d6aff828c341a53034950fc9.zip.