/pandas 0.23


DatetimeIndex.tz_localize(tz, ambiguous='raise', errors='raise') [source]

Localize tz-naive DatetimeIndex to tz-aware DatetimeIndex.

This method takes a time zone (tz) naive DatetimeIndex object and makes this time zone aware. It does not move the time to another time zone. Time zone localization helps to switch from time zone aware to time zone unaware objects.


tz : string, pytz.timezone, dateutil.tz.tzfile or None

Time zone to convert timestamps to. Passing None will remove the time zone information preserving local time.

ambiguous : str {‘infer’, ‘NaT’, ‘raise’} or bool array, default ‘raise’

  • ‘infer’ will attempt to infer fall dst-transition hours based on order
  • bool-ndarray where True signifies a DST time, False signifies a non-DST time (note that this flag is only applicable for ambiguous times)
  • ‘NaT’ will return NaT where there are ambiguous times
  • ‘raise’ will raise an AmbiguousTimeError if there are ambiguous times

errors : {‘raise’, ‘coerce’}, default ‘raise’

  • ‘raise’ will raise a NonExistentTimeError if a timestamp is not
    valid in the specified time zone (e.g. due to a transition from or to DST time)
  • ‘coerce’ will return NaT if the timestamp can not be converted to the specified time zone

New in version 0.19.0.



Index converted to the specified time zone.



If the DatetimeIndex is tz-aware and tz is not None.

See also

Convert tz-aware DatetimeIndex from one time zone to another.


>>> tz_naive = pd.date_range('2018-03-01 09:00', periods=3)
>>> tz_naive
DatetimeIndex(['2018-03-01 09:00:00', '2018-03-02 09:00:00',
               '2018-03-03 09:00:00'],
              dtype='datetime64[ns]', freq='D')

Localize DatetimeIndex in US/Eastern time zone:

>>> tz_aware = tz_naive.tz_localize(tz='US/Eastern')
>>> tz_aware
DatetimeIndex(['2018-03-01 09:00:00-05:00',
               '2018-03-02 09:00:00-05:00',
               '2018-03-03 09:00:00-05:00'],
              dtype='datetime64[ns, US/Eastern]', freq='D')

With the tz=None, we can remove the time zone information while keeping the local time (not converted to UTC):

>>> tz_aware.tz_localize(None)
DatetimeIndex(['2018-03-01 09:00:00', '2018-03-02 09:00:00',
               '2018-03-03 09:00:00'],
              dtype='datetime64[ns]', freq='D')

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Licensed under the 3-clause BSD License.