diff --git a/homeassistant/components/demo/weather.py b/homeassistant/components/demo/weather.py
index b17c88fa828..3c87cd1c27c 100644
--- a/homeassistant/components/demo/weather.py
+++ b/homeassistant/components/demo/weather.py
@@ -4,6 +4,7 @@ from datetime import timedelta
 from homeassistant.components.weather import (
     ATTR_FORECAST_CONDITION,
     ATTR_FORECAST_PRECIPITATION,
+    ATTR_FORECAST_PRECIPITATION_PROBABILITY,
     ATTR_FORECAST_TEMP,
     ATTR_FORECAST_TEMP_LOW,
     ATTR_FORECAST_TIME,
@@ -48,13 +49,13 @@ def setup_platform(hass, config, add_entities, discovery_info=None):
                 0.5,
                 TEMP_CELSIUS,
                 [
-                    ["rainy", 1, 22, 15],
-                    ["rainy", 5, 19, 8],
-                    ["cloudy", 0, 15, 9],
-                    ["sunny", 0, 12, 6],
-                    ["partlycloudy", 2, 14, 7],
-                    ["rainy", 15, 18, 7],
-                    ["fog", 0.2, 21, 12],
+                    ["rainy", 1, 22, 15, 60],
+                    ["rainy", 5, 19, 8, 30],
+                    ["cloudy", 0, 15, 9, 10],
+                    ["sunny", 0, 12, 6, 0],
+                    ["partlycloudy", 2, 14, 7, 20],
+                    ["rainy", 15, 18, 7, 0],
+                    ["fog", 0.2, 21, 12, 100],
                 ],
             ),
             DemoWeather(
@@ -66,13 +67,13 @@ def setup_platform(hass, config, add_entities, discovery_info=None):
                 4.8,
                 TEMP_FAHRENHEIT,
                 [
-                    ["snowy", 2, -10, -15],
-                    ["partlycloudy", 1, -13, -14],
-                    ["sunny", 0, -18, -22],
-                    ["sunny", 0.1, -23, -23],
-                    ["snowy", 4, -19, -20],
-                    ["sunny", 0.3, -14, -19],
-                    ["sunny", 0, -9, -12],
+                    ["snowy", 2, -10, -15, 60],
+                    ["partlycloudy", 1, -13, -14, 25],
+                    ["sunny", 0, -18, -22, 70],
+                    ["sunny", 0.1, -23, -23, 90],
+                    ["snowy", 4, -19, -20, 40],
+                    ["sunny", 0.3, -14, -19, 0],
+                    ["sunny", 0, -9, -12, 0],
                 ],
             ),
         ]
@@ -163,6 +164,7 @@ class DemoWeather(WeatherEntity):
                 ATTR_FORECAST_PRECIPITATION: entry[1],
                 ATTR_FORECAST_TEMP: entry[2],
                 ATTR_FORECAST_TEMP_LOW: entry[3],
+                ATTR_FORECAST_PRECIPITATION_PROBABILITY: entry[4],
             }
             reftime = reftime + timedelta(hours=4)
             forecast_data.append(data_dict)
diff --git a/homeassistant/components/environment_canada/weather.py b/homeassistant/components/environment_canada/weather.py
index 10666b4a34e..7bc614bd09e 100644
--- a/homeassistant/components/environment_canada/weather.py
+++ b/homeassistant/components/environment_canada/weather.py
@@ -8,6 +8,7 @@ import voluptuous as vol
 
 from homeassistant.components.weather import (
     ATTR_FORECAST_CONDITION,
+    ATTR_FORECAST_PRECIPITATION_PROBABILITY,
     ATTR_FORECAST_TEMP,
     ATTR_FORECAST_TEMP_LOW,
     ATTR_FORECAST_TIME,
@@ -183,6 +184,9 @@ def get_forecast(ec_data, forecast_type):
                     ATTR_FORECAST_CONDITION: icon_code_to_condition(
                         int(half_days[0]["icon_code"])
                     ),
+                    ATTR_FORECAST_PRECIPITATION_PROBABILITY: int(
+                        half_days[0]["precip_probability"]
+                    ),
                 }
             )
             half_days = half_days[2:]
@@ -200,6 +204,9 @@ def get_forecast(ec_data, forecast_type):
                     ATTR_FORECAST_CONDITION: icon_code_to_condition(
                         int(half_days[high]["icon_code"])
                     ),
+                    ATTR_FORECAST_PRECIPITATION_PROBABILITY: int(
+                        half_days[high]["precip_probability"]
+                    ),
                 }
             )
 
@@ -215,6 +222,9 @@ def get_forecast(ec_data, forecast_type):
                     ATTR_FORECAST_CONDITION: icon_code_to_condition(
                         int(hours[hour]["icon_code"])
                     ),
+                    ATTR_FORECAST_PRECIPITATION_PROBABILITY: int(
+                        hours[hour]["precip_probability"]
+                    ),
                 }
             )
 
diff --git a/homeassistant/components/weather/__init__.py b/homeassistant/components/weather/__init__.py
index 8efb8519636..5a6fcc2d80b 100644
--- a/homeassistant/components/weather/__init__.py
+++ b/homeassistant/components/weather/__init__.py
@@ -19,6 +19,7 @@ ATTR_CONDITION_CLASS = "condition_class"
 ATTR_FORECAST = "forecast"
 ATTR_FORECAST_CONDITION = "condition"
 ATTR_FORECAST_PRECIPITATION = "precipitation"
+ATTR_FORECAST_PRECIPITATION_PROBABILITY = "precipitation_probability"
 ATTR_FORECAST_TEMP = "temperature"
 ATTR_FORECAST_TEMP_LOW = "templow"
 ATTR_FORECAST_TIME = "datetime"
diff --git a/tests/components/weather/test_weather.py b/tests/components/weather/test_weather.py
index 10161a0d634..ccddb35ad0a 100644
--- a/tests/components/weather/test_weather.py
+++ b/tests/components/weather/test_weather.py
@@ -6,6 +6,7 @@ from homeassistant.components.weather import (
     ATTR_FORECAST,
     ATTR_FORECAST_CONDITION,
     ATTR_FORECAST_PRECIPITATION,
+    ATTR_FORECAST_PRECIPITATION_PROBABILITY,
     ATTR_FORECAST_TEMP,
     ATTR_FORECAST_TEMP_LOW,
     ATTR_WEATHER_ATTRIBUTION,
@@ -56,12 +57,20 @@ class TestWeather(unittest.TestCase):
         assert data.get(ATTR_WEATHER_ATTRIBUTION) == "Powered by Home Assistant"
         assert data.get(ATTR_FORECAST)[0].get(ATTR_FORECAST_CONDITION) == "rainy"
         assert data.get(ATTR_FORECAST)[0].get(ATTR_FORECAST_PRECIPITATION) == 1
+        assert (
+            data.get(ATTR_FORECAST)[0].get(ATTR_FORECAST_PRECIPITATION_PROBABILITY)
+            == 60
+        )
         assert data.get(ATTR_FORECAST)[0].get(ATTR_FORECAST_TEMP) == 22
         assert data.get(ATTR_FORECAST)[0].get(ATTR_FORECAST_TEMP_LOW) == 15
         assert data.get(ATTR_FORECAST)[6].get(ATTR_FORECAST_CONDITION) == "fog"
         assert data.get(ATTR_FORECAST)[6].get(ATTR_FORECAST_PRECIPITATION) == 0.2
         assert data.get(ATTR_FORECAST)[6].get(ATTR_FORECAST_TEMP) == 21
         assert data.get(ATTR_FORECAST)[6].get(ATTR_FORECAST_TEMP_LOW) == 12
+        assert (
+            data.get(ATTR_FORECAST)[6].get(ATTR_FORECAST_PRECIPITATION_PROBABILITY)
+            == 100
+        )
         assert len(data.get(ATTR_FORECAST)) == 7
 
     def test_temperature_convert(self):