diff --git a/examples/weather/graphcast/validation_base.py b/examples/weather/graphcast/validation_base.py
index 765285cfe..f119d616c 100644
--- a/examples/weather/graphcast/validation_base.py
+++ b/examples/weather/graphcast/validation_base.py
@@ -82,7 +82,9 @@ def step(self, channels=[0, 1, 2], iter=0, time_idx=None):
             "num_samples_per_year": self.num_samples_per_year_train,
             "device": self.dist.device,
         }
-        for i, data in enumerate(self.val_datapipe):
+        val_data_iter = iter(itertools.islice(self.val_datapipe, len(self.val_datapipe)))
+        for i in range(len(self.val_datapipe)):
+            data = next(val_data_iter)
             invar = data[0]["invar"]
             outvar = data[0]["outvar"][0]
             try: