diff --git a/climax/main/preprocess/preprocess_ERA5.py b/climax/main/preprocess/preprocess_ERA5.py
index 89cf258abcad1b7176f469ddaf2771a46e91c950..3f061fbbeb499d360d589ea704807c61133e852e 100644
--- a/climax/main/preprocess/preprocess_ERA5.py
+++ b/climax/main/preprocess/preprocess_ERA5.py
@@ -94,7 +94,8 @@ if __name__ == '__main__':
 
                 # compute daily averages/sums
                 if var == 'total_precipitation':
-                    ds = ds.resample(time='D').sum(dim='time')
+                    # convert from m to mm
+                    ds = ds.resample(time='D').sum(dim='time') * 1000
                 else:
                     ds = ds.resample(time='D').mean(dim='time')