The default Apple Weather application cannot display information for users anywhere in the world. Some users’ outages lasted hours, while others lasted days. The issue appears to be a server-side issue with Apple’s System Status Dashboard page, which shows current issues with the Weather app. The details on the page only show Alaska as an issue, but the issue persists for users all over the world.
Apple Weather app is down
Strangely, the weather app on some Apple devices (including MacBook and Apple Watch) does not exhibit this issue for some users. In our own testing, we managed to recover a few minutes of weather data in the app by manually adding a location via the search bar in the Weather app. We can expect Apple to fix the bug soon.
Source