The iOS app often shows scattered thunderstorms while the website shows scattered showers. The website is right, the app not. This bug in the app has been for years now and it does not seem to get fixed.
Jum Per commented
I searched the web and found that there seems to be a bug or change in Yahoos API. Weather! Code 39 is actually „scattered showers“. But in some documentation this is labeled as „scattered thunderstorms“. So the fix in the iOS App should be easy. Hopefully someone will take care of this.