watchOS 5.3.10 (build 16U711) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2026-03-24T18:34:20Z. The update package is 66.99 MB. This is a delta (partial) update that requires 5.3 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: ec94abbb8c12dcf23fd0ffc78f6f6f804a3e54e3.zip.