I developed a sensor to check whether the current day is a holiday (state = on if so). I use this sensor for automation - only play sound in the morning on workdays, not weekend nor holidays. I used python module “holidays” which must be installed with pip (https://pypi.python.org/pypi/holidays/0.5).
This is my first python script 
.
Please have mercy. I hope it works for your need. Unfortunately I had to put the script in the directory home-assistant/components/sensors. If I put it into custom_components it will not be loaded. I don’t know why. If someone has an idea, please tell me.
"""
Sensor to check whether current date is a holiday.
"""
import asyncio
import logging
import voluptuous as vol
from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import (STATE_ON, STATE_OFF, CONF_NAME)
import homeassistant.util.dt as dt_util
from homeassistant.helpers.entity import Entity
import homeassistant.helpers.config_validation as cv
_LOGGER = logging.getLogger(__name__)
REQUIREMENTS = ['holidays==0.5']
ALL_COUNTRIES = ['AU', 'AT', 'CA', 'CO', 'DK', 'DE', 'MX', 'NZ', 'ES',
'UK', 'US']
CONF_COUNTRY = 'country'
CONF_PROVINCE = 'province'
DEFAULT_NAME = 'Holiday Sensor'
PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
vol.Required(CONF_COUNTRY): vol.In(ALL_COUNTRIES),
vol.Optional(CONF_PROVINCE, default=None): cv.string,
vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
})
@asyncio.coroutine
def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
"""Setup the Holiday sensor."""
import holidays
name = config.get(CONF_NAME)
country = None
country = config.get(CONF_COUNTRY)
obj_holidays = getattr(holidays, country)()
province = config.get(CONF_PROVINCE)
if province:
if province not in obj_holidays.PROVINCES:
_LOGGER.error('There is no province/state %s in country %s',
province, country)
return False
else:
obj_holidays = getattr(holidays, country)(state=province)
yield from async_add_devices([IsHolidaySensor(obj_holidays, name)], True)
return True
class IsHolidaySensor(Entity):
"""Implementation of a Holiday sensor."""
def __init__(self, obj_holidays, name):
"""Initialize the sensor."""
self._name = name
self._obj_holidays = obj_holidays
self._state = None
@property
def name(self):
"""Return the name of the sensor."""
return self._name
@property
def state(self):
"""Return the state of the device."""
return self._state
@asyncio.coroutine
def async_update(self):
"""Get date and look whether it is a holiday."""
self._date = dt_util.now()
if self._date in self._obj_holidays:
self._state = STATE_ON
else:
self._state = STATE_OFF
