There may be several reasons why the weather data doesn't update and this is not always the app's fault. This may be a dropped Internet connection or other occasional glitches.
These simple steps will help you to quickly mitigate a one-time issue:
1. Update the data manually. You just need to tap the screen of the app, drag it down and then release.
2. Restart the app. For this, access the multitasking screen by double tapping the home button on the device and swipe right to see the pages with recently opened apps. Swipe the app's page up in order to force quit the app then tap the home button once to get back to the device's main screen.
If you still experience glitches or have questions, let us know at firstname.lastname@example.org.