watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2026-02-02T18:44:22Z. The update package is 214.71 MB. This is a delta (partial) update that requires 6.2.8 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: c7e70bba7164510f06e33f2ab19bb2cc4b59b617.zip.