Banking hours are usually 08.30-15.30 Monday-Friday (excluding public holidays). Thailand is well served by a network of ATMs, particularly in the major towns and resorts. In addition, exchange kiosks with extended opening hours can be found in most of the main tourist areas. A better exchange rate is normally available inside Thailand than from your home country and it makes sense to wait until you arrive in Thailand before changing large amounts of money into Thai baht. Bangkok’s new international airport has ATMs and exchange kiosks in the arrival hall.
The main banks which usually display the Visa/Mastercard/Cirrus sign at their ATMs are:
Thai Farmers Bank
Bank of Ayudhaya
Bangkok Bank
Siam Commercial Bank
Your bank in your home country may add a handling charge on to any cash withdrawals you make via an ATM in Thailand. To avoid any unwelcome surprises when you get back home, it is always best to check the amount of these charges before you travel.
Update: From April 2009, Thai banks are introducing an ATM withdrawal fee for cards registered overseas.
An up to date list of exchange rates is available from the Bangkok Bank website.