No? Or not necessarily, at least. For example, pytz (a Python timezone library) offers "is_dst" flags for exactly that purpose. >>> loc_dt = datetime(2002, 1

No? Or not necessarily, at least. For example, pytz (a Python timezone library) offers "is_dst" flags for exactly that purpose. >>> loc_dt = datetime(2002, 10, 27, 1, 30, 00) >>> est_dt = eastern.localize(loc_dt, is_dst=True) >>> edt_dt = eastern.localize(loc_dt, is_dst=False) >>> print(est_dt.strftime(fmt) + ' / ' + edt_dt.strftime(fmt)) 2002-10-27 01:30:00 EDT-0400 / 2002-10-27 01:30:00 EST-0500 https://pythonhosted.org/pytz/#problems-with-localtime https://pythonhosted.org/pytz/#problems-with-localtime