Point to Variable or DataArray constructor in non-nanosecond warning

Author: spencerkclark

xarray/core/variable.py

@@ -71,7 +71,10 @@
 NON_NANOSECOND_WARNING = (
     "Converting non-nanosecond precision {case} values to nanosecond precision. "
     "This behavior can eventually be relaxed in xarray, as it is an artifact from "
-    "pandas which is now beginning to support non-nanosecond precision values."
+    "pandas which is now beginning to support non-nanosecond precision values. "
+    "This warning is caused by passing non-nanosecond np.datetime64 or "
+    "np.timedelta64 values to the DataArray or Variable constructor; it can be "
+    "silenced by converting the values to nanosecond precision ahead of time."
 )
 
 
@@ -191,14 +194,14 @@ def _as_nanosecond_precision(data):
         isinstance(dtype, pd.DatetimeTZDtype) and dtype.unit != "ns"
     )
     if non_ns_datetime64 or non_ns_datetime_tz_dtype:
-        warnings.warn(NON_NANOSECOND_WARNING.format(case="datetime"))
+        warnings.warn(NON_NANOSECOND_WARNING.format(case="datetime"), stacklevel=5)
         if isinstance(dtype, pd.DatetimeTZDtype):
             nanosecond_precision_dtype = pd.DatetimeTZDtype("ns", dtype.tz)
         else:
             nanosecond_precision_dtype = "datetime64[ns]"
         return data.astype(nanosecond_precision_dtype)
     elif dtype.kind == "m" and dtype != np.dtype("timedelta64[ns]"):
-        warnings.warn(NON_NANOSECOND_WARNING.format(case="timedelta"))
+        warnings.warn(NON_NANOSECOND_WARNING.format(case="timedelta"), stacklevel=5)
         return data.astype("timedelta64[ns]")
     else:
         return data