For a very liminted travel dates within May and June you may consider current deal of Ukraine International airlines. They are now offering cheap flights to Bangkok out of main tourist season. To reach the cheapest fare possible you have to depart ex Amsterdam. Such a roundtrip flights are available from just €389! You may also consider to depart ex Germany (Frankfurt, Munich, Berlin) where the flights are available for around €440.
During the May and June you may expect unpredictable weather in Bangkok with possible storms but it is also the least expensive time to visit. If you are planning to visit Thailand during this year period you may consider this offer of Ukraine International airlines. The flights have just one short layover in Kiev making it ideal routing to this destination in South-East Asia. However, the flights are available in very limited travel options and quantity.pPease see below travel date samples based on departures from Netherlands currently available for €389.
Booking sample Amsterdam – Bangkok for €389
Travel date samples
7. – 23.5.
14. – 26.5.
4. – 20.6.
13. – 30.6.
Booking sample of a roundtrip flight from Europe to Thailand for just €389 below. The cheapest flights to Bangkok are available when departing from Amsterdam. In this case you would be flying to Bangkok on 14th of May and returning back from Thailand on 26th of May 2014.