Don Goldberg1 wrote:
On my iMac, the default widget for the Weather app was working up until a few weeks ago. Now I get an error message, simply saying "weather unavailable." This appears in the widget and in the desktop app, although I am still able to get custom readings for cities stored in the app. I thought upgrading Tahoe to 26.0.1 might solve the issue, but it remains. My attempts to refresh the default widget have failed thus far, and I am at a loss on what to do now.
Apple Weather app is unavailable check that Location Services is enabled for it in Settings...
Toggle some changes, then come back to your preferred settings.

Same for Date & Time ie automatic for Location Toggle some changes, then come back to your preferred setting and compare your results

no resolve—
A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies
certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled temporarily.
Login and test. Reboot as normal and test. Caches get rebuilt automatically.
The current stable release of Tahoe including bug fixes, security updates is macOS 26.0.1
Keep your Mac up to date - Apple Support
Keep your Mac up to date - Apple Support
To be proactive you can file a bug report / submit your Apple Feedback here:
Feedback - Weather - Apple