diff --git a/homeassistant/helpers/entity.py b/homeassistant/helpers/entity.py
index f6ff8c73bf5..75ac1e0c1b8 100644
--- a/homeassistant/helpers/entity.py
+++ b/homeassistant/helpers/entity.py
@@ -295,6 +295,9 @@ class Entity(ABC):
     # If we reported this entity is updated while disabled
     _disabled_reported = False
 
+    # If we reported this entity is relying on deprecated temperature conversion
+    _temperature_reported = False
+
     # Protect for multiple updates
     _update_staged = False
 
@@ -642,23 +645,57 @@ class Entity(ABC):
         if DATA_CUSTOMIZE in self.hass.data:
             attr.update(self.hass.data[DATA_CUSTOMIZE].get(self.entity_id))
 
-        # Convert temperature if we detect one
-        try:
+        def _convert_temperature(state: str, attr: dict) -> str:
+            # Convert temperature if we detect one
+            # pylint: disable-next=import-outside-toplevel
+            from homeassistant.components.sensor import SensorEntity
+
             unit_of_measure = attr.get(ATTR_UNIT_OF_MEASUREMENT)
             units = self.hass.config.units
-            domain = split_entity_id(self.entity_id)[0]
-            if (
-                unit_of_measure in (TEMP_CELSIUS, TEMP_FAHRENHEIT)
-                and unit_of_measure != units.temperature_unit
-                and domain != "sensor"
+            if unit_of_measure == units.temperature_unit or unit_of_measure not in (
+                TEMP_CELSIUS,
+                TEMP_FAHRENHEIT,
             ):
+                return state
+
+            domain = split_entity_id(self.entity_id)[0]
+            if domain != "sensor":
+                if not self._temperature_reported:
+                    self._temperature_reported = True
+                    report_issue = self._suggest_report_issue()
+                    _LOGGER.warning(
+                        "Entity %s (%s) relies on automatic temperature conversion, this will "
+                        "be unsupported in Home Assistant Core 2022.7. Please %s",
+                        self.entity_id,
+                        type(self),
+                        report_issue,
+                    )
+            elif not isinstance(self, SensorEntity):
+                if not self._temperature_reported:
+                    self._temperature_reported = True
+                    report_issue = self._suggest_report_issue()
+                    _LOGGER.warning(
+                        "Temperature sensor %s (%s) does not inherit SensorEntity, "
+                        "this will be unsupported in Home Assistant Core 2022.7."
+                        "Please %s",
+                        self.entity_id,
+                        type(self),
+                        report_issue,
+                    )
+            else:
+                return state
+
+            try:
                 prec = len(state) - state.index(".") - 1 if "." in state else 0
                 temp = units.temperature(float(state), unit_of_measure)
                 state = str(round(temp) if prec == 0 else round(temp, prec))
                 attr[ATTR_UNIT_OF_MEASUREMENT] = units.temperature_unit
-        except ValueError:
-            # Could not convert state to float
-            pass
+            except ValueError:
+                # Could not convert state to float
+                pass
+            return state
+
+        state = _convert_temperature(state, attr)
 
         if (
             self._context_set is not None
diff --git a/tests/helpers/test_entity.py b/tests/helpers/test_entity.py
index afc0887371e..9130de04e0f 100644
--- a/tests/helpers/test_entity.py
+++ b/tests/helpers/test_entity.py
@@ -13,6 +13,7 @@ from homeassistant.const import (
     ATTR_DEVICE_CLASS,
     STATE_UNAVAILABLE,
     STATE_UNKNOWN,
+    TEMP_FAHRENHEIT,
 )
 from homeassistant.core import Context, HomeAssistantError
 from homeassistant.helpers import entity, entity_registry
@@ -814,6 +815,64 @@ async def test_float_conversion(hass):
     assert state.state == "3.6"
 
 
+async def test_temperature_conversion(hass, caplog):
+    """Test conversion of temperatures."""
+    # Non sensor entity reporting a temperature
+    with patch.object(
+        entity.Entity, "state", PropertyMock(return_value=100)
+    ), patch.object(
+        entity.Entity, "unit_of_measurement", PropertyMock(return_value=TEMP_FAHRENHEIT)
+    ):
+        ent = entity.Entity()
+        ent.hass = hass
+        ent.entity_id = "hello.world"
+        ent.async_write_ha_state()
+
+    state = hass.states.get("hello.world")
+    assert state is not None
+    assert state.state == "38"
+    assert (
+        "Entity hello.world (<class 'homeassistant.helpers.entity.Entity'>) relies on automatic "
+        "temperature conversion, this will be unsupported in Home Assistant Core 2022.7. "
+        "Please create a bug report" in caplog.text
+    )
+
+    # Sensor entity, not extending SensorEntity, reporting a temperature
+    with patch.object(
+        entity.Entity, "state", PropertyMock(return_value=100)
+    ), patch.object(
+        entity.Entity, "unit_of_measurement", PropertyMock(return_value=TEMP_FAHRENHEIT)
+    ):
+        ent = entity.Entity()
+        ent.hass = hass
+        ent.entity_id = "sensor.temp"
+        ent.async_write_ha_state()
+
+    state = hass.states.get("sensor.temp")
+    assert state is not None
+    assert state.state == "38"
+    assert (
+        "Temperature sensor sensor.temp (<class 'homeassistant.helpers.entity.Entity'>) "
+        "does not inherit SensorEntity, this will be unsupported in Home Assistant Core "
+        "2022.7.Please create a bug report" in caplog.text
+    )
+
+    # Sensor entity, not extending SensorEntity, not reporting a number
+    with patch.object(
+        entity.Entity, "state", PropertyMock(return_value="really warm")
+    ), patch.object(
+        entity.Entity, "unit_of_measurement", PropertyMock(return_value=TEMP_FAHRENHEIT)
+    ):
+        ent = entity.Entity()
+        ent.hass = hass
+        ent.entity_id = "sensor.temp"
+        ent.async_write_ha_state()
+
+    state = hass.states.get("sensor.temp")
+    assert state is not None
+    assert state.state == "really warm"
+
+
 async def test_attribution_attribute(hass):
     """Test attribution attribute."""
     mock_entity = entity.Entity()