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Backport of the standard library zoneinfo module

Project description

backports.zoneinfo: Backport of the standard library module zoneinfo

This package was originally the reference implementation for PEP 615, which proposes support for the IANA time zone database in the standard library, and now serves as a backport to Python 3.6+ (including PyPy).

This exposes the backports.zoneinfo module, which is a backport of the zoneinfo module. The backport's documentation can be found on readthedocs.

The module uses the system time zone data if available, and falls back to the tzdata package (available on PyPI) if installed.

Installation and depending on this library

This module is called backports.zoneinfo on PyPI. To install it in your local environment, use:

pip install backports.zoneinfo

Or (particularly on Windows), you can also use the tzdata extra (which basically just declares a dependency on tzdata, so this doesn't actually save you any typing 😅):

pip install backports.zoneinfo[tzdata]

If you want to use this in your application, it is best to use PEP 508 environment markers to declare a dependency conditional on the Python version:


Support for backports.zoneinfo in Python 3.9+ is currently minimal, since it is expected that you would use the standard library zoneinfo module instead.


The backports.zoneinfo module should be a drop-in replacement for the Python 3.9 standard library module zoneinfo. If you do not support anything earlier than Python 3.9, you do not need this library; if you are supporting Python 3.6+, you may want to use this idiom to "fall back" to backports.zoneinfo:

    import zoneinfo
except ImportError:
    from backports import zoneinfo

To get access to time zones with this module, construct a ZoneInfo object and attach it to your datetime:

>>> from backports.zoneinfo import ZoneInfo
>>> from datetime import datetime, timedelta, timezone
>>> dt = datetime(1992, 3, 1, tzinfo=ZoneInfo("Europe/Minsk"))
>>> print(dt)
1992-03-01 00:00:00+02:00
>>> print(dt.utcoffset())
>>> print(dt.tzname())

Arithmetic works as expected without the need for a "normalization" step:

>>> dt += timedelta(days=90)
>>> print(dt)
1992-05-30 00:00:00+03:00
>>> dt.utcoffset()
>>> dt.tzname()

Ambiguous and imaginary times are handled using the fold attribute added in PEP 495:

>>> dt = datetime(2020, 11, 1, 1, tzinfo=ZoneInfo("America/Chicago"))
>>> print(dt)
2020-11-01 01:00:00-05:00
>>> print(dt.replace(fold=1))
2020-11-01 01:00:00-06:00

>>> UTC = timezone.utc
>>> print(dt.astimezone(UTC))
2020-11-01 06:00:00+00:00
>>> print(dt.replace(fold=1).astimezone(UTC))
2020-11-01 07:00:00+00:00


Currently we are not accepting contributions to this repository because we have not put the CLA in place and we would like to avoid complicating the process of adoption into the standard library. Contributions to CPython will eventually be backported to this repository — see the Python developer's guide for more information on how to contribute to CPython.

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