diff --git a/src/access_moppy/qc/cmip7.py b/src/access_moppy/qc/cmip7.py
index 6da894a3..a3b8a174 100644
--- a/src/access_moppy/qc/cmip7.py
+++ b/src/access_moppy/qc/cmip7.py
@@ -93,7 +93,12 @@ def _is_outside_allowed_range(observed: float, minimum: float, maximum: float) -
     ``-6e-24`` are treated as zero for a lower bound of ``0``.
     """
 
-    tolerance = 1e-12
+    # Many CMIP outputs are derived from float32 fields where boundary values
+    # (for example 100%) can round to slightly above/below the nominal limit.
+    # Use a scale-aware absolute tolerance so closed-interval checks remain
+    # robust without masking meaningfully out-of-range values.
+    scale = max(abs(observed), abs(minimum), abs(maximum), 1.0)
+    tolerance = max(1e-12, 8.0 * np.finfo(np.float32).eps * scale)
     lower_violation = observed < minimum and not np.isclose(
         observed, minimum, rtol=0.0, atol=tolerance
     )
diff --git a/tests/unit/test_cmip7_qc.py b/tests/unit/test_cmip7_qc.py
index e562f2ed..f2b3f0f4 100644
--- a/tests/unit/test_cmip7_qc.py
+++ b/tests/unit/test_cmip7_qc.py
@@ -178,6 +178,21 @@ def test_validate_cmip7_output_allows_tiny_negative_noise_at_zero_bound(tmp_path
     validate_cmip7_output(path)
 
 
+@pytest.mark.unit
+def test_validate_cmip7_output_allows_float32_boundary_noise_for_percent_range(
+    tmp_path,
+):
+    path = _write_cmip7_output(
+        tmp_path,
+        values=[0.0, 100.00003],
+        experiment_id="historical",
+        variable_id="snc",
+        units="%",
+    )
+
+    validate_cmip7_output(path)
+
+
 @pytest.mark.unit
 def test_validate_cmip7_output_tas_fails_for_picontrol_range(tmp_path):
     path = _write_cmip7_output(