diff --git a/pysteps/blending/steps.py b/pysteps/blending/steps.py
index 1cffa8bd..4edb3929 100644
--- a/pysteps/blending/steps.py
+++ b/pysteps/blending/steps.py
@@ -3167,7 +3167,7 @@ def __post_process_output(
         # areas with the "..._mod_only" blended forecasts, consisting
         # of the NWP and noise components.
         nan_indices = np.isnan(worker_state.final_blended_forecast_recomposed)
-        if self.__config.smooth_radar_mask_range != 0:
+        if self.__config.smooth_radar_mask_range != 0 and np.any(nan_indices):
             # Compute the smooth dilated mask
             new_mask = blending.utils.compute_smooth_dilated_mask(
                 nan_indices,