It's working for me again now but worth noting the status page never indicated any problems and the issue persisted for several hours.

Can't speak for anyone else in this thread but it's been working for me since about 4 hours or so after my post 3 days ago. You might be experiencing a "new" issue.

Cool, so Apple engineers are watching the forums... how come no comments on any of the threads about the very frequent 401 errors, and overall instability vs the Dark Sky API many of us have been forced to switch from?

Thanks for the info about the TSI. They don't make it easy on developers new to their ecosystem to find the proper place to file issues. I'll likely try and submit one of those.

FWIW I have seen stability with the REST API for 3+ days now after experiencing huge problems with the 401 errors, sometimes as much as a 50% return rate. I have changed nothing (as in, I did not set an earlier token issue time) so it's possible that things are just better at the moment on the Apple side vs that actually being a fix. That said, I really appreciate you sharing this and if the 401s become a problem again I will try this change.