They fixed the issue, but apparently missed including my api key.
http://status.darksky.net/2018/05/03/authentication-errors.html
3 May 2018 • Downtime
Between 2:30 AM ET and 9:00 AM ET, a small percentage of users were unable to authenticate with the API. (This manifested as a 403 Forbidden HTTP error when making an API call.)
This was caused by an issue with our authentication database. We have fixed the immediate issue (authentication for these users now goes through), but the Dark Sky API developer site will have limited functionality for the next couple hours while we finish cleaning up.