import numpy as np
import pandas as pd
import xarray as xr

time = np.arange('2007-02-01', '2007-03-02', dtype='datetime64').astype('datetime64[ns]')
arr = xr.DataArray(
    np.arange(time.size), coords=[time,], dims=('time',), name='data'
)
arr.resample(time='M').interpolate('linear')

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-20-ff65c4d138e7> in <module>()
      7     np.arange(time.size), coords=[time,], dims=('time',), name='data'
      8 )
----> 9 arr.resample(time='M').interpolate('linear')

~/devel/c3s-cns/venv_op/lib/python3.6/site-packages/xarray/core/resample.py in interpolate(self, kind)
    108 
    109         """
--> 110         return self._interpolate(kind=kind)
    111 
    112     def _interpolate(self, kind='linear'):

~/devel/c3s-cns/venv_op/lib/python3.6/site-packages/xarray/core/resample.py in _interpolate(self, kind)
    218             elif self._dim not in v.dims:
    219                 coords[k] = v
--> 220         return DataArray(f(new_x), coords, dims, name=dummy.name,
    221                          attrs=dummy.attrs)
    222 

~/devel/c3s-cns/venv_op/lib/python3.6/site-packages/scipy/interpolate/polyint.py in __call__(self, x)
     77         """
     78         x, x_shape = self._prepare_x(x)
---> 79         y = self._evaluate(x)
     80         return self._finish_y(y, x_shape)
     81 

~/devel/c3s-cns/venv_op/lib/python3.6/site-packages/scipy/interpolate/interpolate.py in _evaluate(self, x_new)
    632         y_new = self._call(self, x_new)
    633         if not self._extrapolate:
--> 634             below_bounds, above_bounds = self._check_bounds(x_new)
    635             if len(y_new) > 0:
    636                 # Note fill_value must be broadcast up to the proper size

~/devel/c3s-cns/venv_op/lib/python3.6/site-packages/scipy/interpolate/interpolate.py in _check_bounds(self, x_new)
    664                              "range.")
    665         if self.bounds_error and above_bounds.any():
--> 666             raise ValueError("A value in x_new is above the interpolation "
    667                              "range.")
    668 

ValueError: A value in x_new is above the interpolation range.

time = np.arange('2007-02-01', '2007-03-01', dtype='datetime64').astype('datetime64[ns]')
arr = xr.DataArray(
    np.arange(time.size), coords=[time,], dims=('time',), name='data'
)
arr.resample(time='M').interpolate('linear')

<xarray.DataArray 'data' (time: 1)>
array([27.])
Coordinates:
  * time     (time) datetime64[ns] 2007-02-28

resampler = arr.resample(time='M') 

resampler._full_index
DatetimeIndex(['2007-02-28', '2007-03-31'], dtype='datetime64[ns]', name='time', freq='M')

<xarray.DataArray 'data' (time: 1)>
array([27.])
Coordinates:
  * time     (time) datetime64[ns] 2007-02-28