SELECT '1-1-2014 02:00:00'::timestamp at time zone 'America/Los_Angeles';

2014-01-01 02:00:00-08

SELECT CAST('1-1-2014 02:00:00'::timestamp at time zone 'America/Los_Angeles' AS Date);

2014-01-01

SELECT CAST('1-1-2014 00:02:00'::timestamp at time zone 'America/Los_Angeles' AS Date) at time zone 'America/Los_Angeles';

2014-01-01 00:00:00

SELECT '1-1-2014 02:00:00'::timestamp at time zone 'UTC' at time zone 'America/Los_Angeles';
      timezone
---------------------
 2013-12-31 18:00:00

SELECT '1-1-2014 02:00:00'::timestamp + INTERVAL '1 hour' * extract(timezone_hour FROM '1-1-2014 00:02:00'::timestamp at time zone 'America/Los_Angeles');

SELECT ('2014-01-01 02:00:00'::timestamp AT TIME ZONE 'UTC')::date

SELECT '2014-01-01 02:00:00+0'::timestamptz::date