Please be aware that Yogyakarta has multiple airports and that these results are for all airports serving the city.
The best month to fly between Yogyakarta and Surabaya is February and the most expensive month to fly is September. (Average prices, based on 591 datapoints.)
The best day to arrive at Yogyakarta is Saturday and it would be best to avoid Monday, as prices are on average 13.93% higher than on Saturday. (Average prices, based on 591 datapoints.)