Dark Sky has been acquired by Apple and is no longer allowing new registrations for their API and will be completely shut down on March 31st, 2023.
New users will no longer be able to obtain an API key which is a necessary requirement to configure the Dark Sky integration in Home Assistant. The Home Assistant website features alternative weather integrations.
For existing users that have already obtained an API key, the Dark Sky API will continue to function until the end of
Update June 7, 2021: Support for the Dark Sky API service for existing customers will continue until the end of 2022.
Update June 6, 2022: Support for the Dark Sky API service for existing customers will continue until March 31st, 2023.
Please see their blog post for more information: https://blog.darksky.net/.