diff --git a/homeassistant/components/alexa/capabilities.py b/homeassistant/components/alexa/capabilities.py
index dfb97cd9db2..d769f797da1 100644
--- a/homeassistant/components/alexa/capabilities.py
+++ b/homeassistant/components/alexa/capabilities.py
@@ -11,6 +11,7 @@ from homeassistant.const import (
     STATE_ON,
     STATE_UNAVAILABLE,
     STATE_UNLOCKED,
+    STATE_UNKNOWN,
 )
 import homeassistant.components.climate.const as climate
 from homeassistant.components import light, fan, cover
@@ -443,7 +444,17 @@ class AlexaTemperatureSensor(AlexaCapibility):
         if self.entity.domain == climate.DOMAIN:
             unit = self.hass.config.units.temperature_unit
             temp = self.entity.attributes.get(climate.ATTR_CURRENT_TEMPERATURE)
-        return {"value": float(temp), "scale": API_TEMP_UNITS[unit]}
+
+        if temp in (STATE_UNAVAILABLE, STATE_UNKNOWN):
+            return None
+
+        try:
+            temp = float(temp)
+        except ValueError:
+            _LOGGER.warning("Invalid temp value %s for %s", temp, self.entity.entity_id)
+            return None
+
+        return {"value": temp, "scale": API_TEMP_UNITS[unit]}
 
 
 class AlexaContactSensor(AlexaCapibility):
@@ -591,4 +602,12 @@ class AlexaThermostatController(AlexaCapibility):
         if temp is None:
             return None
 
-        return {"value": float(temp), "scale": API_TEMP_UNITS[unit]}
+        try:
+            temp = float(temp)
+        except ValueError:
+            _LOGGER.warning(
+                "Invalid temp value %s for %s in %s", temp, name, self.entity.entity_id
+            )
+            return None
+
+        return {"value": temp, "scale": API_TEMP_UNITS[unit]}
diff --git a/tests/components/alexa/__init__.py b/tests/components/alexa/__init__.py
index f853c4ef848..48406a11aef 100644
--- a/tests/components/alexa/__init__.py
+++ b/tests/components/alexa/__init__.py
@@ -171,6 +171,12 @@ class ReportedProperties:
         """Initialize class."""
         self.properties = properties
 
+    def assert_not_has_property(self, namespace, name):
+        """Assert a property does not exist."""
+        for prop in self.properties:
+            if prop["namespace"] == namespace and prop["name"] == name:
+                assert False, "Property %s:%s exists"
+
     def assert_equal(self, namespace, name, value):
         """Assert a property is equal to a given value."""
         for prop in self.properties:
diff --git a/tests/components/alexa/test_capabilities.py b/tests/components/alexa/test_capabilities.py
index f8ad3f57c42..357e0e3026d 100644
--- a/tests/components/alexa/test_capabilities.py
+++ b/tests/components/alexa/test_capabilities.py
@@ -1,7 +1,15 @@
 """Test Alexa capabilities."""
 import pytest
 
-from homeassistant.const import STATE_LOCKED, STATE_UNLOCKED, STATE_UNKNOWN
+from homeassistant.const import (
+    ATTR_UNIT_OF_MEASUREMENT,
+    TEMP_CELSIUS,
+    STATE_LOCKED,
+    STATE_UNLOCKED,
+    STATE_UNKNOWN,
+    STATE_UNAVAILABLE,
+)
+from homeassistant.components import climate
 from homeassistant.components.alexa import smart_home
 from tests.common import async_mock_service
 
@@ -368,3 +376,47 @@ async def test_report_cover_percentage_state(hass):
 
     properties = await reported_properties(hass, "cover.closed")
     properties.assert_equal("Alexa.PercentageController", "percentage", 0)
+
+
+async def test_temperature_sensor_sensor(hass):
+    """Test TemperatureSensor reports sensor temperature correctly."""
+    for bad_value in (STATE_UNKNOWN, STATE_UNAVAILABLE, "not-number"):
+        hass.states.async_set(
+            "sensor.temp_living_room",
+            bad_value,
+            {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS},
+        )
+
+        properties = await reported_properties(hass, "sensor.temp_living_room")
+        properties.assert_not_has_property("Alexa.TemperatureSensor", "temperature")
+
+    hass.states.async_set(
+        "sensor.temp_living_room", "34", {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS}
+    )
+    properties = await reported_properties(hass, "sensor.temp_living_room")
+    properties.assert_equal(
+        "Alexa.TemperatureSensor", "temperature", {"value": 34.0, "scale": "CELSIUS"}
+    )
+
+
+async def test_temperature_sensor_climate(hass):
+    """Test TemperatureSensor reports climate temperature correctly."""
+    for bad_value in (STATE_UNKNOWN, STATE_UNAVAILABLE, "not-number"):
+        hass.states.async_set(
+            "climate.downstairs",
+            climate.HVAC_MODE_HEAT,
+            {climate.ATTR_CURRENT_TEMPERATURE: bad_value},
+        )
+
+        properties = await reported_properties(hass, "climate.downstairs")
+        properties.assert_not_has_property("Alexa.TemperatureSensor", "temperature")
+
+    hass.states.async_set(
+        "climate.downstairs",
+        climate.HVAC_MODE_HEAT,
+        {climate.ATTR_CURRENT_TEMPERATURE: 34},
+    )
+    properties = await reported_properties(hass, "climate.downstairs")
+    properties.assert_equal(
+        "Alexa.TemperatureSensor", "temperature", {"value": 34.0, "scale": "CELSIUS"}
+    )