diff --git a/homeassistant/components/environment_canada/weather.py b/homeassistant/components/environment_canada/weather.py
index 2d54a313dde..1871062c2e9 100644
--- a/homeassistant/components/environment_canada/weather.py
+++ b/homeassistant/components/environment_canada/weather.py
@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from typing import Any
+
 from homeassistant.components.weather import (
     ATTR_CONDITION_CLEAR_NIGHT,
     ATTR_CONDITION_CLOUDY,
@@ -190,10 +192,12 @@ def get_forecast(ec_data, hourly) -> list[Forecast] | None:
         if not (half_days := ec_data.daily_forecasts):
             return None
 
-        def get_day_forecast(fcst: list[dict[str, str]]) -> Forecast:
+        def get_day_forecast(
+            fcst: list[dict[str, Any]],
+        ) -> Forecast:
             high_temp = int(fcst[0]["temperature"]) if len(fcst) == 2 else None
             return {
-                ATTR_FORECAST_TIME: fcst[0]["timestamp"],
+                ATTR_FORECAST_TIME: fcst[0]["timestamp"].isoformat(),
                 ATTR_FORECAST_NATIVE_TEMP: high_temp,
                 ATTR_FORECAST_NATIVE_TEMP_LOW: int(fcst[-1]["temperature"]),
                 ATTR_FORECAST_PRECIPITATION_PROBABILITY: int(
diff --git a/tests/components/environment_canada/conftest.py b/tests/components/environment_canada/conftest.py
new file mode 100644
index 00000000000..69cec187d11
--- /dev/null
+++ b/tests/components/environment_canada/conftest.py
@@ -0,0 +1,27 @@
+"""Common fixture for Environment Canada tests."""
+
+import contextlib
+from datetime import datetime
+import json
+
+import pytest
+
+from tests.common import load_fixture
+
+
+@pytest.fixture
+def ec_data():
+    """Load Environment Canada data."""
+
+    def date_hook(weather):
+        """Convert timestamp string to datetime."""
+
+        if t := weather.get("timestamp"):
+            with contextlib.suppress(ValueError):
+                weather["timestamp"] = datetime.fromisoformat(t)
+        return weather
+
+    return json.loads(
+        load_fixture("environment_canada/current_conditions_data.json"),
+        object_hook=date_hook,
+    )
diff --git a/tests/components/environment_canada/snapshots/test_weather.ambr b/tests/components/environment_canada/snapshots/test_weather.ambr
index 7ba37110c2a..cfa0ad912a4 100644
--- a/tests/components/environment_canada/snapshots/test_weather.ambr
+++ b/tests/components/environment_canada/snapshots/test_weather.ambr
@@ -5,35 +5,35 @@
       'forecast': list([
         dict({
           'condition': 'sunny',
-          'datetime': '2022-10-04 15:00:00+00:00',
+          'datetime': '2022-10-04T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 18.0,
           'templow': 3.0,
         }),
         dict({
           'condition': 'sunny',
-          'datetime': '2022-10-05 15:00:00+00:00',
+          'datetime': '2022-10-05T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 20.0,
           'templow': 9.0,
         }),
         dict({
           'condition': 'partlycloudy',
-          'datetime': '2022-10-06 15:00:00+00:00',
+          'datetime': '2022-10-06T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 20.0,
           'templow': 7.0,
         }),
         dict({
           'condition': 'rainy',
-          'datetime': '2022-10-07 15:00:00+00:00',
+          'datetime': '2022-10-07T15:00:00+00:00',
           'precipitation_probability': 40,
           'temperature': 13.0,
           'templow': 1.0,
         }),
         dict({
           'condition': 'partlycloudy',
-          'datetime': '2022-10-08 15:00:00+00:00',
+          'datetime': '2022-10-08T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 10.0,
           'templow': 3.0,
@@ -48,42 +48,42 @@
       'forecast': list([
         dict({
           'condition': 'clear-night',
-          'datetime': '2022-10-03 15:00:00+00:00',
+          'datetime': '2022-10-03T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': None,
           'templow': -1.0,
         }),
         dict({
           'condition': 'sunny',
-          'datetime': '2022-10-04 15:00:00+00:00',
+          'datetime': '2022-10-04T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 18.0,
           'templow': 3.0,
         }),
         dict({
           'condition': 'sunny',
-          'datetime': '2022-10-05 15:00:00+00:00',
+          'datetime': '2022-10-05T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 20.0,
           'templow': 9.0,
         }),
         dict({
           'condition': 'partlycloudy',
-          'datetime': '2022-10-06 15:00:00+00:00',
+          'datetime': '2022-10-06T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 20.0,
           'templow': 7.0,
         }),
         dict({
           'condition': 'rainy',
-          'datetime': '2022-10-07 15:00:00+00:00',
+          'datetime': '2022-10-07T15:00:00+00:00',
           'precipitation_probability': 40,
           'temperature': 13.0,
           'templow': 1.0,
         }),
         dict({
           'condition': 'partlycloudy',
-          'datetime': '2022-10-08 15:00:00+00:00',
+          'datetime': '2022-10-08T15:00:00+00:00',
           'precipitation_probability': 0,
           'temperature': 10.0,
           'templow': 3.0,
diff --git a/tests/components/environment_canada/test_diagnostics.py b/tests/components/environment_canada/test_diagnostics.py
index 7e9c8691f90..79b72961124 100644
--- a/tests/components/environment_canada/test_diagnostics.py
+++ b/tests/components/environment_canada/test_diagnostics.py
@@ -1,6 +1,7 @@
 """Test Environment Canada diagnostics."""
 
 import json
+from typing import Any
 
 from syrupy import SnapshotAssertion
 
@@ -26,6 +27,7 @@ async def test_entry_diagnostics(
     hass: HomeAssistant,
     hass_client: ClientSessionGenerator,
     snapshot: SnapshotAssertion,
+    ec_data: dict[str, Any],
 ) -> None:
     """Test config entry diagnostics."""
 
diff --git a/tests/components/environment_canada/test_weather.py b/tests/components/environment_canada/test_weather.py
index e8c21e2dc06..8e22f68462f 100644
--- a/tests/components/environment_canada/test_weather.py
+++ b/tests/components/environment_canada/test_weather.py
@@ -1,6 +1,7 @@
 """Test weather."""
 
-import json
+import copy
+from typing import Any
 
 from syrupy.assertion import SnapshotAssertion
 
@@ -12,23 +13,17 @@ from homeassistant.core import HomeAssistant
 
 from . import init_integration
 
-from tests.common import load_fixture
-
 
 async def test_forecast_daily(
-    hass: HomeAssistant,
-    snapshot: SnapshotAssertion,
+    hass: HomeAssistant, snapshot: SnapshotAssertion, ec_data: dict[str, Any]
 ) -> None:
     """Test basic forecast."""
 
-    ec_data = json.loads(
-        load_fixture("environment_canada/current_conditions_data.json")
-    )
-
     # First entry in test data is a half day; we don't want that for this test
-    del ec_data["daily_forecasts"][0]
+    local_ec_data = copy.deepcopy(ec_data)
+    del local_ec_data["daily_forecasts"][0]
 
-    await init_integration(hass, ec_data)
+    await init_integration(hass, local_ec_data)
 
     response = await hass.services.async_call(
         WEATHER_DOMAIN,
@@ -44,15 +39,10 @@ async def test_forecast_daily(
 
 
 async def test_forecast_daily_with_some_previous_days_data(
-    hass: HomeAssistant,
-    snapshot: SnapshotAssertion,
+    hass: HomeAssistant, snapshot: SnapshotAssertion, ec_data: dict[str, Any]
 ) -> None:
     """Test forecast with half day at start."""
 
-    ec_data = json.loads(
-        load_fixture("environment_canada/current_conditions_data.json")
-    )
-
     await init_integration(hass, ec_data)
 
     response = await hass.services.async_call(