Getting computer's UTC offset in Python

Question

In Python, how do you find what UTC time offset the computer is set to?

Answer 1

time.timezone:

import time

print -time.timezone

It prints UTC offset in seconds (to take into account Daylight Saving Time (DST) see time.altzone:

is_dst = time.daylight and time.localtime().tm_isdst > 0
utc_offset = - (time.altzone if is_dst else time.timezone)

where utc offset is defined via: "To get local time, add utc offset to utc time."

In Python 3.3+ there is tm_gmtoff attribute if underlying C library supports it:

utc_offset = time.localtime().tm_gmtoff

Note: time.daylight may give a wrong result in some edge cases.

tm_gmtoff is used automatically by datetime if it is available on Python 3.3+:

from datetime import datetime, timedelta, timezone

d = datetime.now(timezone.utc).astimezone()
utc_offset = d.utcoffset() // timedelta(seconds=1)

To get the current UTC offset in a way that workarounds the time.daylight issue and that works even if tm_gmtoff is not available, @jts's suggestion to substruct the local and UTC time can be used:

import time
from datetime import datetime

ts = time.time()
utc_offset = (datetime.fromtimestamp(ts) -
              datetime.utcfromtimestamp(ts)).total_seconds()

To get UTC offset for past/future dates, pytz timezones could be used:

from datetime import datetime
from tzlocal import get_localzone # $ pip install tzlocal

tz = get_localzone() # local timezone 
d = datetime.now(tz) # or some other local date 
utc_offset = d.utcoffset().total_seconds()

It works during DST transitions, it works for past/future dates even if the local timezone had different UTC offset at the time e.g., Europe/Moscow timezone in 2010-2015 period.