From 402a0ea7dac4cb4f88afa1d862fee637ad1f9648 Mon Sep 17 00:00:00 2001
From: Philip Allgaier <mail@spacegaier.de>
Date: Thu, 14 Jan 2021 08:47:45 +0100
Subject: [PATCH] Fix OpenWeatherMap forecast timestamp (#45124)

---
 homeassistant/components/openweathermap/sensor.py      | 10 +++++++++-
 .../openweathermap/weather_update_coordinator.py       |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/homeassistant/components/openweathermap/sensor.py b/homeassistant/components/openweathermap/sensor.py
index 39c50c3b941..b1ba4ab7625 100644
--- a/homeassistant/components/openweathermap/sensor.py
+++ b/homeassistant/components/openweathermap/sensor.py
@@ -1,7 +1,10 @@
 """Support for the OpenWeatherMap (OWM) service."""
+import datetime
+
 from .abstract_owm_sensor import AbstractOpenWeatherMapSensor
 from .const import (
     ATTR_API_FORECAST,
+    DEVICE_CLASS_TIMESTAMP,
     DOMAIN,
     ENTRY_NAME,
     ENTRY_WEATHER_COORDINATOR,
@@ -95,5 +98,10 @@ class OpenWeatherMapForecastSensor(AbstractOpenWeatherMapSensor):
         """Return the state of the device."""
         forecasts = self._weather_coordinator.data.get(ATTR_API_FORECAST)
         if forecasts is not None and len(forecasts) > 0:
-            return forecasts[0].get(self._sensor_type, None)
+            value = forecasts[0].get(self._sensor_type, None)
+            if self._device_class is DEVICE_CLASS_TIMESTAMP:
+                value = datetime.datetime.fromtimestamp(
+                    value, datetime.timezone.utc
+                ).isoformat()
+            return value
         return None
diff --git a/homeassistant/components/openweathermap/weather_update_coordinator.py b/homeassistant/components/openweathermap/weather_update_coordinator.py
index b4ddb40c046..605e6f9edc1 100644
--- a/homeassistant/components/openweathermap/weather_update_coordinator.py
+++ b/homeassistant/components/openweathermap/weather_update_coordinator.py
@@ -138,7 +138,7 @@ class WeatherUpdateCoordinator(DataUpdateCoordinator):
 
     def _convert_forecast(self, entry):
         forecast = {
-            ATTR_FORECAST_TIME: entry.reference_time("unix") * 1000,
+            ATTR_FORECAST_TIME: entry.reference_time("unix"),
             ATTR_FORECAST_PRECIPITATION: self._calc_precipitation(
                 entry.rain, entry.snow
             ),