I know today is a bank holiday and the rates quoted for foreign exchange by Bangkok Bank are yesterdays

I have a Foreign currency account that I can transfer to baht

If I did a transfer today would the rate be as yesterday or a rate from international markets today

you will probably get the lowest rate over the said period.

...would the rate be as yesterday or a rate from international markets today .....

I think, there will be not too much difference

I think it's whatever the last currency exchange update (used by that particular bank) was on the previous/last business day. So if the last update was Update #3 on Friday (last business day) and you are exchanging money on Sunday on a realtime/at a counter basis, you will get the Friday's Update #3 rate.

If you were doing some money movement/exchange online, then the exchange rate is probably going to be Update #1 for the following/next business day (i.e., Monday) when the transaction would probably be posted unless the bank has a rule that certain transactions will occur within "X" amount business days...say 2 business days, 3 business days, etc. Different banks have different rules.

Edited May 28, 201016 yr by Pib

You will get the last updated rate from Fridays close of business.

If you did it after the bank closed, you will get the opening rate or the rate at the time funds arrive in THB at your bank. That will be the rates next week.

The last update of a Friday will always be on the low side, as that rate is used throughout the weekend for cash exchanges at exchange boots. The banks are covering themselves for a potential loss in case the exchange rate opens lower on Monday.

I assume for transfers from a FCA to a Thai Baht account within the same bank they will do the same, i.e. use Friday's rate...