diff --git a/sdm/models/kumo/timeseries/forecast/model.py b/sdm/models/kumo/timeseries/forecast/model.py
index 7f6b8e075..b312ef67c 100644
--- a/sdm/models/kumo/timeseries/forecast/model.py
+++ b/sdm/models/kumo/timeseries/forecast/model.py
@@ -197,7 +197,15 @@ def _forward(
             assert y_context is not None
             y_schema = y_context.schema
             x = y_context.numerical
-            if x_context_only is not None:
+            if x_context_only is not None and x_context_only.size(-1) > 0:
+                if self.model.cross_channel is None:
+                    warn_once(
+                        key="kumo-forecast-historical-covariate",
+                        message=(
+                            "Historical covariates have no effect when "
+                            "'cross_channel' is disabled."
+                        ),
+                    )
                 x = torch.cat([x, x_context_only.numerical], dim=-1)
 
             x = x[..., -self.model.context_size :, :].transpose(-1, -2)