Apple today announced that it will be releasing watchOS 6 on Thursday, September 19 for the Apple Watch Series 3 and Series 4 models.
watchOS 6 will not be immediately available on Series 1 and Series 2 Apple Watch models, with Apple instead delaying the release until "later this fall."
It is not clear why older Apple Watch models won't be getting the update at launch.
September 19 is just one day before new Apple Watch Series 5 models are expected to begin shipping out. Apple Watch Series 5 pre-orders are available starting today on Apple.com.