watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2026-02-02T18:44:19Z. The update package is 733.21 MB. This is a delta (partial) update that requires 6.0.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 95c896b648a88974bda1fa23277eb46aa4f95c61.zip.