diff --git a/mlair/run_modules/pre_processing.py b/mlair/run_modules/pre_processing.py
index 5710b63336b5c3e505363b90215a8cb631c3da22..d56d064ad618b1dbae7b9c8b08a5887e8577dcbe 100644
--- a/mlair/run_modules/pre_processing.py
+++ b/mlair/run_modules/pre_processing.py
@@ -295,11 +295,12 @@ class PreProcessing(RunEnvironment):
         else:  # serial solution
             logging.info("use serial validate station approach")
             kwargs.update({"return_strategy": "result"})
-            for station in set_stations:
+            for i, station in enumerate(set_stations):
                 dh, s = f_proc(data_handler, station, set_name, store_processed_data, **kwargs)
                 if dh is not None:
                     collection.add(dh)
                     valid_stations.append(s)
+                logging.info(f"...finished: {s} ({int((i + 1.) / len(set_stations) * 100)}%)")
 
         logging.info(f"run for {t_outer} to check {len(set_stations)} station(s). Found {len(collection)}/"
                      f"{len(set_stations)} valid stations ({set_name}).")