This was happening to me as well. To fix it, I dragged the Weather app (not the widget) out of a group of apps, then I opened the Weather App. At that point, the Weather widget started working again and I saw it in the list of widgets to add when editing widgets.
I’m not sure if moving the App or opening it is what fixed the issues. It continued to work when I put the weather app back where it was originally.
JakeAllan
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