Using arrow

arrow_samples.py

# http://arrow.readthedocs.io/en/latest/

# when you to('local') you are taking utc and applying the localtime offset
# to it - and adding the local timezone descriptor to the object
now = arrow.utcnow().to('local')

# plural means add or subtract from
# singular means set to
# nice!
two_days_ago_rounded = now.replace(days=-2, hour=0, minute=0, second=0, microsecond=1)

# Setting the timezone on a time - this does not convert it! 
# It marks the object as being in the requested timezone.
two_days_ago_rounded.replace(tzinfo=tz.tzlocal())