watchOS 5.3 (build 16U5558b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-06-24T17:25:13Z. The update package is 157.58 MB. This is a delta (partial) update that requires 5.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fbd4bbe1707b5bc8693ae4014b5ada40232320e8.zip.