The specific Dark Sky feature no one has cloned adequately is the microforecast that says "it will rain on you in 8 minutes". There's a zillion apps that do a decent job of hourly and daily weather forecasts. But the particular rain warning was something Dark Sky was uniquely good at.
Rain Alarm on Android comes close, and even uses Dark Sky data (for now). But the UI isn't as good and the predictions aren't as accurate.
PS: understand that if you join Apple your work will be consumed and digested by the company in a way that renders your personal identity invisible. This is true both for companies like Dark Sky and for individuals.
MyRadar on iOS does this very well. Has notifications on when rain will start, estimate on duration, warnings if storms are predicted in the next 24 hours, lightning nearby notifications, etc. It appears to be available for Android. I subscribe to MyRadar Pro and find it quite worth it to support the development.
Dark Sky is not among the licenses and attributions. I suspect they generate their end product from various other data sources, much like Dark Sky did.
There is an app for Garmin watches called "Minutecast" which has been pretty accurate at predicting rain periods when it can get my location correct (does not work as well in remote areas that may have few weather stations, based on my personal experience).
Rain Alarm on Android comes close, and even uses Dark Sky data (for now). But the UI isn't as good and the predictions aren't as accurate.
PS: understand that if you join Apple your work will be consumed and digested by the company in a way that renders your personal identity invisible. This is true both for companies like Dark Sky and for individuals.