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 546.48 MB. This is a delta (partial) update that requires 6.1.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: c6092c4e913472b1574c132570217d487d21243e.zip.