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 900 datapoints.)
The best day to arrive at Bangkok is Monday and it would be best to avoid Thursday, as prices are on average 71.97% higher than on Monday. (Average prices, based on 896 datapoints.)
The cheapest airline flying from Bangkok to Hong Kong is Hong Kong Express. They are 52% cheaper than Cathay Pacific. (Average prices, based on 919 datapoints.)
The best time to fly is at around 16. (Average prices, based on 1464 datapoints.)