watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 5 (40mm, LTE), released on 2026-02-02T18:44:51Z. The update package is 165.87 MB. This is a delta (partial) update that requires 6.3 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: a9bad36cae63f36fdd1078850d163051b0ca17a3.zip.