Try this.
1. Navigate to the “Settings” app.
2.Scroll down and tap “Privacy”.
3.Go to “Location Services”.
4.Enable “Location Services”.
5. Now, go to the “Weather” app on the same tab.
6. Tick mark “While Using the App”.
Then, depending on your iPad model.
If your iPad has a Home button,
Do a simple hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.
If you have an iPad with NO Home button
Try the new hard reset procedure for the new 2018 iPad Pro models.
1. Press and release the volume UP button.
2. Then immediately press and release the volume DOWN button.
3. Then, press and hold the Power button at the top. You will see the Slide to Power off button, but keep on holding down the Power button until you see the Apple logo, then let it go.
Once you have performed all the steps, wait for a few seconds and your 2018 iPad Pro will boot up completely to the iPad Pro’s Lock screen.
Good Luck!