This is a great extension presenting you information in a simple manner.

sudo apt install gnome-shell-extension-weather

Then all you have to restart the gnome shell by executing:

Alt+F2

Enter r and press Enter.

Now open up Gnome Tweak Tool and enable Openweather in the Extensions tab.

This app is great for new users.

sudo apt install gnome-weather

Now search for Weather and the app should pop up.

After logging out (and logging back in), the Calendar extension will be displayed.