# xarray.core.resample.DataArrayResample.bfill

#### DataArrayResample.bfill(tolerance=None)[[source]](https://github.com/pydata/xarray/blob/main/xarray/core/resample.py#L161-L184)

Backward fill new values at up-sampled frequency.

* **Parameters:**
  **tolerance** (`float | Iterable[float] | str | None`, *default*: [`None`](https://docs.python.org/3/builtins/constants.html#None)) – Maximum distance between original and new labels to limit
  the up-sampling method.
  Up-sampled data with indices that satisfy the equation
  `abs(index[indexer] - target) <= tolerance` are filled by
  new values. Data with indices that are outside the given
  tolerance are filled with `NaN` s.
* **Returns:**
  **backfilled** ([`DataArray`](xarray.DataArray.html.md#xarray.DataArray) or [`Dataset`](xarray.Dataset.html.md#xarray.Dataset))