Please be aware that Bangkok has multiple airports and that these results are for all airports serving the city.
The best month to fly between Bangkok and Hong Kong is September and the most expensive month to fly is February. (Average prices, based on 624 datapoints.)
The best day to arrive at Bangkok is Monday and it would be best to avoid Wednesday, as prices are on average 63.51% higher than on Monday. (Average prices, based on 354 datapoints.)
The cheapest airline flying from Bangkok to Hong Kong is Hong Kong Express. They are 54% cheaper than Cathay Pacific. (Average prices, based on 640 datapoints.)
The best time to fly is at around 10. (Average prices, based on 980 datapoints.)