diff --git a/homeassistant/components/sensor/wunderground.py b/homeassistant/components/sensor/wunderground.py
index 82bb3d3b245..3194afbe94e 100644
--- a/homeassistant/components/sensor/wunderground.py
+++ b/homeassistant/components/sensor/wunderground.py
@@ -7,6 +7,7 @@ https://home-assistant.io/components/sensor.wunderground/
 from datetime import timedelta
 import logging
 
+import re
 import requests
 import voluptuous as vol
 
@@ -172,7 +173,8 @@ class WUndergroundSensor(Entity):
     def entity_picture(self):
         """Return the entity picture."""
         if self._condition == 'weather':
-            return self.rest.data['icon_url']
+            url = self.rest.data['icon_url']
+            return re.sub(r'^http://', 'https://', url, flags=re.IGNORECASE)
 
     @property
     def unit_of_measurement(self):
diff --git a/tests/components/sensor/test_wunderground.py b/tests/components/sensor/test_wunderground.py
index cde94558866..05c7fc93921 100644
--- a/tests/components/sensor/test_wunderground.py
+++ b/tests/components/sensor/test_wunderground.py
@@ -25,7 +25,7 @@ VALID_CONFIG = {
 
 FEELS_LIKE = '40'
 WEATHER = 'Clear'
-ICON_URL = 'http://icons.wxug.com/i/c/k/clear.gif'
+HTTPS_ICON_URL = 'https://icons.wxug.com/i/c/k/clear.gif'
 ALERT_MESSAGE = 'This is a test alert message'
 
 
@@ -61,7 +61,7 @@ def mocked_requests_get(*args, **kwargs):
                 },
                 "feelslike_c": FEELS_LIKE,
                 "weather": WEATHER,
-                "icon_url": ICON_URL,
+                "icon_url": 'http://icons.wxug.com/i/c/k/clear.gif',
                 "display_location": {
                     "city": "Holly Springs",
                     "country": "US",
@@ -150,7 +150,7 @@ class TestWundergroundSetup(unittest.TestCase):
             device.update()
             self.assertTrue(str(device.name).startswith('PWS_'))
             if device.name == 'PWS_weather':
-                self.assertEqual(ICON_URL, device.entity_picture)
+                self.assertEqual(HTTPS_ICON_URL, device.entity_picture)
                 self.assertEqual(WEATHER, device.state)
                 self.assertIsNone(device.unit_of_measurement)
             elif device.name == 'PWS_alerts':