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 Medan is October and the most expensive month to fly is December. (Average prices, based on 1960 datapoints.)
The best day to arrive at Yogyakarta is Friday and it would be best to avoid Tuesday, as prices are on average 15.37% higher than on Friday. (Average prices, based on 1958 datapoints.)