import dateutil.parser as dp
s = 'Sat, 11/01/09 8:00PM'
for tz_code in ('PST', 'PDT', 'MST', 'MDT', 'CST', 'CDT', 'EST', 'EDT'):
    dt = s + ' ' + tz_code
print(dt, '=', dp.parse(dt, tzinfos=tzd))
Parsing date/time string with timezone abbreviated name in Python?