BUG: `np.isnan` raises on pyarrow dtypes

[MarcoGorelli]

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• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

hm that's raising for me
In [1]: import pandas as pd

In [2]: pd.set_option("mode.nan_is_na", False)

In [3]: s = pd.Series([-1, 0, None], dtype='Int64[pyarrow]')**.5

In [4]: s
Out[4]:
0     NaN
1     0.0
2    <NA>
dtype: double[pyarrow]

In [5]: import numpy as np

In [6]: np.isnan(s)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[6], line 1
----> 1 np.isnan(s)

File ~/scratch/.venv/lib/python3.12/site-packages/pandas/core/generic.py:2051, in NDFrame.__array_ufunc__(self, ufunc, method, *inputs, **kwargs)
   2047 @final
   2048 def __array_ufunc__(
   2049     self, ufunc: np.ufunc, method: str, *inputs: Any, **kwargs: Any
   2050 ):
-> 2051     return arraylike.array_ufunc(self, ufunc, method, *inputs, **kwargs)

File ~/scratch/.venv/lib/python3.12/site-packages/pandas/core/arraylike.py:399, in array_ufunc(self, ufunc, method, *inputs, **kwargs)
    396 elif self.ndim == 1:
    397     # ufunc(series, ...)
    398     inputs = tuple(extract_array(x, extract_numpy=True) for x in inputs)
--> 399     result = getattr(ufunc, method)(*inputs, **kwargs)
    400 else:
    401     # ufunc(dataframe)
    402     if method == "__call__" and not kwargs:
    403         # for np.<ufunc>(..) calls
    404         # kwargs cannot necessarily be handled block-by-block, so only
    405         # take this path if there are no kwargs

File ~/scratch/.venv/lib/python3.12/site-packages/pandas/core/arrays/base.py:2539, in ExtensionArray.__array_ufunc__(self, ufunc, method, *inputs, **kwargs)
   2536     if result is not NotImplemented:
   2537         return result
-> 2539 return arraylike.default_array_ufunc(self, ufunc, method, *inputs, **kwargs)

File ~/scratch/.venv/lib/python3.12/site-packages/pandas/core/arraylike.py:492, in default_array_ufunc(self, ufunc, method, *inputs, **kwargs)
    488     raise NotImplementedError
    490 new_inputs = [x if x is not self else np.asarray(x) for x in inputs]
--> 492 return getattr(ufunc, method)(*new_inputs, **kwargs)

TypeError: ufunc 'isnan' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

Issue Description

it raises

Expected Behavior

I'd have expected

[True, False, NA]

output

Installed Versions

INSTALLED VERSIONS

commit : e97a56e
python : 3.12.5
python-bits : 64
OS : Linux
OS-release : 6.6.87.2-microsoft-standard-WSL2
Version : #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : C.UTF-8
LOCALE : C.UTF-8

pandas : 3.0.0.dev0+2451.ge97a56e746
numpy : 2.3.3
dateutil : 2.9.0.post0
pip : 25.0.1
Cython : None
sphinx : None
IPython : 9.2.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.13.4
bottleneck : None
fastparquet : None
fsspec : 2025.9.0
html5lib : None
hypothesis : None
gcsfs : 2025.2.0
jinja2 : 3.1.6
lxml.etree : None
matplotlib : 3.10.3
numba : None
numexpr : None
odfpy : None
openpyxl : None
psycopg2 : None
pymysql : None
pyarrow : 21.0.0
pyiceberg : None
pyreadstat : None
pytest : None
python-calamine : None
pytz : 2025.2
pyxlsb : None
s3fs : None
scipy : 1.16.0
sqlalchemy : None
tables : None
tabulate : 0.9.0
xarray : None
xlrd : None
xlsxwriter : None
zstandard : None
qtpy : None
pyqt5 : None

[jbrockmendel]

We're going to need to add to ArrowEA.__array_ufunc__ something like:

if not nan_is_na() and ufunc is np.isnan:
    if self.dtype.kind == "f":
        return pc.is_nan(self._pa_array).to_numpy()
    return np.zeros(self.shape, dtype=bool)