diff --git a/toargridding/grids.py b/toargridding/grids.py
index cb140672f97a3c4c60cd9819b2952d401792fbf9..fe7cd2360c0a9eca92278ec853526aaee921116e 100644
--- a/toargridding/grids.py
+++ b/toargridding/grids.py
@@ -144,6 +144,7 @@ class RegularGrid(GridDefinition):
 
     def create_gridded_statistics(self, time, grouped_timeseries):
         values = np.empty((self.lat.size, self.lon.size, time.size))
+        values[...] = self.fill_value
 
         index = self._as_xy_index[grouped_timeseries.index]
         values[index.T[0], index.T[1]] = grouped_timeseries.values.reshape(