Add Rio de Janeiro (Brazil) to your list and use my-locations table to visually convert it's time to another timezone or city time.
Mouse over the colored hour-tiles and glance at the hours selected by the column.

Current time zone for Rio de Janeiro (Brazil) is America/Sao_Paulo, whose offset is GMT-3 from Greenwich Mean Time (GMT).

The IANA timezone identifier for Rio de Janeiro, Brazil is "America/Sao_Paulo"

It currently does not observe Daylight Savings Time.