Fix OWM async I/O (#4298)

homeassistant/components/weather/openweathermap.py

@@ -67,7 +67,7 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
     data = WeatherData(owm, latitude, longitude)
 
     add_devices([OpenWeatherMapWeather(
-        name, data, hass.config.units.temperature_unit)])
+        name, data, hass.config.units.temperature_unit)], True)
 
 
 class OpenWeatherMapWeather(WeatherEntity):
@@ -78,8 +78,7 @@ class OpenWeatherMapWeather(WeatherEntity):
         self._name = name
         self._owm = owm
         self._temperature_unit = temperature_unit
-        self.date = None
-        self.update()
+        self.data = None
 
     @property
     def name(self):