Latvia Guide
Entry requirements
Citizens of the US, EU member states, Australia, New Zealand and Canada are allowed visa-free entry into Latvia. Nationals of other countries should check on visa regulations at the relevant embassy or consulate before setting out.
Visitors are allowed to stay in Latvia for a total of ninety days in any given calendar year. If you wish to stay longer than this you'll need to apply for a residence or work permit – simply crossing the border and re-entering again every ninety days won't work. Up-to-date information on entrance regulations and visa costs can be found on the websites of the foreign ministry: 
www.mfa.gov.lv or www.am.gov.lv