Python timezone with DST if pytz unavailable

python_tz_dst

from datetime import timedelta, datetime, tzinfo

# Taken from http://stackoverflow.com/questions/6558535/python-find-the-date-for-the-first-monday-after-a-given-a-date
def next_weekday(d, weekday):
    days_ahead = weekday - d.weekday()
    if days_ahead <= 0: # Target day already happened this week
        days_ahead += 7
    return d + timedelta(days_ahead)

class USEastern(tzinfo):
    def utcoffset(self, dt):
        return timedelta(hours=-5) + self.dst(dt)
    def dst(self, dt):
        # DST starts second Sunday in March
        d = datetime(dt.year, 3, 1)
        self.dston = next_weekday(next_weekday(d, 6), 6)
        # and ends first Sunday in November
        d = datetime(dt.year, 11, 1)
        self.dstoff = next_weekday(d, 6)
        if self.dston <= dt.replace(tzinfo=None) < self.dstoff:
            return timedelta(hours=+1)
        else:
            return timedelta(0)
    def tzname(self,dt):
        return "GMT -5"

datetime.now(tz=USEastern())