Please be aware that Johannesburg has multiple airports and that these results are for all airports serving the city.
The best month to fly between Johannesburg and Cape Town is September and the most expensive month to fly is December. (Average prices, based on 522 datapoints.)
The best day to arrive at Johannesburg is Tuesday and it would be best to avoid Thursday, as prices are on average 39.61% higher than on Tuesday. (Average prices, based on 460 datapoints.)
The best time to fly is at around 10. (Average prices, based on 579 datapoints.)