Just as the title says, how can I add a recurring event on the last Saturday in August in Google Calendar?
Create your first event on the appropriate day.
Then, on the "Event edit" screen, open the "Repeat..." menu.
- For Repeats:, choose "Monthly"
- For Repeat every:, choose "12" months
- For Repeat by:, choose "day of the week"
- Choose whatever other options you need, then click "Done"
This might get a little tricky if a month has only four Saturdays and that's what you use, as Google might not know whether to select "fourth Saturday" or "last Saturday".