The problem has been fixed by Apple. The Weather service was indeed “slow or unavailable for some users,” according to the official Apple services system status website.
Here is the original report.
Users from all over the globe are unable to see information on the default Apple weather app. For some users, the disruption has lasted for hours; for others, it has lasted for several days. The Apple system status dashboard screen indicates that there is currently a problem with the Weather app, suggesting that it is a server-side issue. The details on the page only mention Alaska as a problem, but users from all over the globe continue to experience the same problem.
Strangely enough, the issue does not appear for some users on the weather app on some Apple products, including MacBooks and Apple Watches. In our testing, manually adding a place using the Weather app’s search bar allowed us to temporarily restore weather data to the app. Apple is likely to fix the bug as quickly as possible.
