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 very easy to setup.
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.