How to determine if a timezone specific date in the past is daylight saving or not in python?

Question

Is there a way I can check if a specific timezone is in daylight saving in a date I specified?

    test_dt = datetime(year=2015, month=2, day=1)
    pst = pytz.timezone('America/Los_Angeles')
    test_dt = pst.localize(test_dt) 

    # should return False
    is_day_light_saving(test_dt)

It should be arbitrary, but the example is 'America/Los_Angeles' — Kevin, Jun 30 '15 at 18:50
possible duplicate of [Python daylight savings time](http://stackoverflow.com/questions/2881025/python-daylight-savings-time) — Morgan Thrapp, Jun 30 '15 at 18:53
I think `localtime` only returns the current time, I am not exactly sure if you specified `time` and `timezone` in datetime how would you determine the is daylight saving or not — Kevin, Jun 30 '15 at 18:59
related: [Use Python to find out if a timezone currently in daylight savings time](http://stackoverflow.com/a/19968515/4279) — jfs, Jul 01 '15 at 00:34

jfs · Accepted Answer · 2016-03-01T21:58:10.377

Just call the datetime.dst() method:

def is_summer_time(aware_dt):
    assert aware_dt.tzinfo is not None
    assert aware_dt.tzinfo.utcoffset(aware_dt) is not None
    return bool(aware_dt.dst())

Example:

#!/usr/bin/env python
from datetime import datetime
import pytz # $ pip install pytz

naive = datetime(2015, 2, 1)
pacific = pytz.timezone('America/Los_Angeles')
aware = pacific.localize(naive, is_dst=None) 

print(is_summer_time(aware))

It is equivalent to:

bool(pytz.timezone('America/Los_Angeles').dst(datetime(2015, 2, 1), is_dst=None))

score -1 · Answer 2 · edited May 23 '17 at 12:00

In my experience, timezone data is more easily dealt with timezone-sensitive pandas.Timestamp() than datetime. I am pretty sure the timezone-sensitivity infers daylight savings time from the date itself. It is trivial to convert datetime to pandas.timestamp() by first converting it to a numpy.datetime64.

Timestamp(numpy.datetime64('2012-05-01T01:00:00.000000'))

http://wesmckinney.com/blog/easy-high-performance-time-zone-handling-in-pandas-0-8-0/

python pandas TimeStamps to local time string with daylight saving

Converting between datetime, Timestamp and datetime64

Also you can try looking at the pandas source code and figuring out how it deduced the tz information. https://github.com/pydata/pandas/blob/master/pandas/src/datetime/np_datetime.c

How to determine if a timezone specific date in the past is daylight saving or not in python?

2 Answers2