It could be an issue with Yahoo but I think it is more an issue from the iPhone, maybe trying to collect GPS data to send to yahoo. Or a bug somewhere in that process.
The app is still misbehaving now and then, but still works most of the time.
I got used to the default iPhone weather app so I love it! Very fast (when it updates itself!)
The best way to show "Local Weather" in the Notifications pull down, is to go:
Settings>Privacy>Location Services (ON)>Weather, and select OFF. Once you then go & pull down Notifications, you will have shown whatever city you have chosen on your Weather Widget. ie, if you select Denver on the widget, then Denver will show on the Notification pull down screen. Change location/city, and that city will show when pulling down the Notifications pull down screen.
Hope this helps...