Apple has removed Dark Sky from the App Store ahead of schedule, but developers can still use its API for now. Full story from the iMore Blog...
I used October 1 to finally move Dark Sky into my folder of weather apps and put Apple default in my Home Screen. I am also trying a small stack with 3 weather app widgets in it. The long press and finger motions in default weather app get you what drew me to Dark Sky but not as simply and right there. My use was Dark Sky for short-term weather matters and often Foreca for a longer range view.
FYI or PSA, the Forecast Advisor site finally became mobile friendly. It is a good tool to know the accuracy of different apps and data sources.
I have added Apple's Stock Weather App as one of the complications on my Watch. I was using Carrott, but it never updated automatically.