From version 2.7, you can use GCal for Google Calendar to create Weather Forecast Calendars when you are using macOS Ventura.
1- Go to the application menu, File.
2- The cities selector will then appear.
3- Select a city, for which you want to see the Weather Forecast.
4- Click on the copy button at the bottom.
5- GCal for Google Calendar will open the import from url view.
6- Paste the link, then Click "Add Calendar", and you are done.