diff --git a/pandas/_libs/tslibs/ccalendar.pyx b/pandas/_libs/tslibs/ccalendar.pyx
index 7d58b43e5d460..07c146c06b510 100644
--- a/pandas/_libs/tslibs/ccalendar.pyx
+++ b/pandas/_libs/tslibs/ccalendar.pyx
@@ -54,7 +54,7 @@ weekday_to_int = {int_to_weekday[key]: key for key in int_to_weekday}
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-cpdef inline int32_t get_days_in_month(int year, Py_ssize_t month) nogil:
+cpdef int32_t get_days_in_month(int year, Py_ssize_t month) nogil:
     """Return the number of days in the given month of the given year.
 
     Parameters
diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
index d91283deb9fc7..f79d6f370cc2d 100644
--- a/pandas/_libs/tslibs/conversion.pyx
+++ b/pandas/_libs/tslibs/conversion.pyx
@@ -75,7 +75,7 @@ cdef inline int64_t get_datetime64_nanos(object val) except? -1:
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-def ensure_datetime64ns(ndarray arr, copy=True):
+def ensure_datetime64ns(arr: ndarray, copy: bool=True):
     """
     Ensure a np.datetime64 array has dtype specifically 'datetime64[ns]'
 
@@ -122,7 +122,7 @@ def ensure_datetime64ns(ndarray arr, copy=True):
     return result
 
 
-def ensure_timedelta64ns(ndarray arr, copy=True):
+def ensure_timedelta64ns(arr: ndarray, copy: bint=True):
     """
     Ensure a np.timedelta64 array has dtype specifically 'timedelta64[ns]'
 
@@ -134,14 +134,14 @@ def ensure_timedelta64ns(ndarray arr, copy=True):
     Returns
     -------
     result : ndarray with dtype timedelta64[ns]
-
     """
     return arr.astype(TD_DTYPE, copy=copy)
+    # TODO: check for overflows when going from a lower-resolution to nanos
 
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-def datetime_to_datetime64(object[:] values):
+def datetime_to_datetime64(values: object[:]):
     """
     Convert ndarray of datetime-like objects to int64 array representing
     nanosecond timestamps.
@@ -614,6 +614,8 @@ cpdef inline datetime localize_pydatetime(datetime dt, object tz):
 # ----------------------------------------------------------------------
 # Timezone Conversion
 
+@cython.boundscheck(False)
+@cython.wraparound(False)
 cdef inline int64_t[:] _tz_convert_dst(int64_t[:] values, tzinfo tz,
                                        bint to_utc=True):
     """
@@ -852,14 +854,14 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
     localized : ndarray[int64_t]
     """
     cdef:
-        ndarray[int64_t] trans
+        ndarray[int64_t] trans, result_a, result_b
         int64_t[:] deltas, idx_shifted
-        ndarray ambiguous_array
-        Py_ssize_t i, idx, pos, ntrans, n = len(vals)
-        Py_ssize_t delta_idx_offset, delta_idx
-        int64_t *tdata
+        int64_t[:] result, dst_hours, idx_shifted_left, idx_shifted_right
         int64_t v, left, right, val, v_left, v_right, new_local, remaining_mins
-        ndarray[int64_t] result, result_a, result_b, dst_hours
+        Py_ssize_t i, idx, pos, pos_left, pos_right, ntrans, n = len(vals)
+        Py_ssize_t delta_idx, delta_idx_offset
+        int64_t *tdata
+        ndarray ambiguous_array
         npy_datetimestruct dts
         bint infer_dst = False, is_dst = False, fill = False
         bint shift = False, fill_nonexist = False
@@ -874,7 +876,7 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
         for i in range(n):
             v = vals[i]
             result[i] = _tz_convert_tzlocal_utc(v, tz, to_utc=True)
-        return result
+        return np.asarray(result)
 
     if is_string_object(ambiguous):
         if ambiguous == 'infer':
@@ -936,7 +938,7 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
 
     if infer_dst:
         dst_hours = np.empty(n, dtype=np.int64)
-        dst_hours.fill(NPY_NAT)
+        dst_hours[:] = NPY_NAT
 
         # Get the ambiguous hours (given the above, these are the hours
         # where result_a != result_b and neither of them are NAT)
@@ -977,7 +979,13 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
                 # Pull the only index and adjust
                 a_idx = grp[:switch_idx]
                 b_idx = grp[switch_idx:]
-                dst_hours[grp] = np.hstack((result_a[a_idx], result_b[b_idx]))
+
+                # __setitem__ on dst_hours.base because indexing with
+                #  an ndarray (grp) directly on a memoryview is not supported
+                # TODO: is `grp` necessarily contiguous?  i.e. could we
+                #  equivalently write dst_hours[grp[0]:grp[-1]] = ... ?
+                dst_hours.base[grp] = np.hstack((result_a[a_idx],
+                                                 result_b[b_idx]))
 
     for i in range(n):
         val = vals[i]
@@ -1026,7 +1034,7 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
                 stamp = _render_tstamp(val)
                 raise pytz.NonExistentTimeError(stamp)
 
-    return result
+    return np.asarray(result)
 
 
 cdef inline bisect_right_i8(int64_t *data, int64_t val, Py_ssize_t n):
@@ -1128,7 +1136,7 @@ def normalize_i8_timestamps(int64_t[:] stamps, object tz=None):
                 dt64_to_dtstruct(stamps[i], &dts)
                 result[i] = _normalized_stamp(&dts)
 
-    return result.base  # .base to access underlying np.ndarray
+    return np.asarray(result)
 
 
 @cython.wraparound(False)
@@ -1220,7 +1228,7 @@ cdef inline int64_t _normalized_stamp(npy_datetimestruct *dts) nogil:
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def is_date_array_normalized(int64_t[:] stamps, tz=None):
+def is_date_array_normalized(int64_t[:] stamps, object tz=None):
     """
     Check if all of the given (nanosecond) timestamps are normalized to
     midnight, i.e. hour == minute == second == 0.  If the optional timezone
diff --git a/pandas/_libs/tslibs/fields.pyx b/pandas/_libs/tslibs/fields.pyx
index 216128cae2002..50aa22ae49d7c 100644
--- a/pandas/_libs/tslibs/fields.pyx
+++ b/pandas/_libs/tslibs/fields.pyx
@@ -49,7 +49,7 @@ def build_field_sarray(int64_t[:] dtindex):
     cdef:
         Py_ssize_t i, count = 0
         npy_datetimestruct dts
-        ndarray[int32_t] years, months, days, hours, minutes, seconds, mus
+        int32_t[:] years, months, days, hours, minutes, seconds, mus
 
     count = len(dtindex)
 
@@ -93,7 +93,7 @@ def get_date_name_field(int64_t[:] dtindex, object field, object locale=None):
     """
     cdef:
         Py_ssize_t i, count = 0
-        ndarray[object] out, names
+        object[:] out, names
         npy_datetimestruct dts
         int dow
 
@@ -114,7 +114,7 @@ def get_date_name_field(int64_t[:] dtindex, object field, object locale=None):
             dt64_to_dtstruct(dtindex[i], &dts)
             dow = dayofweek(dts.year, dts.month, dts.day)
             out[i] = names[dow].capitalize()
-        return out
+
     elif field == 'month_name':
         if locale is None:
             names = np.array(MONTHS_FULL, dtype=np.object_)
@@ -128,12 +128,15 @@ def get_date_name_field(int64_t[:] dtindex, object field, object locale=None):
 
             dt64_to_dtstruct(dtindex[i], &dts)
             out[i] = names[dts.month].capitalize()
-        return out
 
-    raise ValueError("Field %s not supported" % field)
+    else:
+        raise ValueError("Field {field} not supported".format(field=field))
+
+    return np.asarray(out)
 
 
 @cython.wraparound(False)
+@cython.boundscheck(False)
 def get_start_end_field(int64_t[:] dtindex, object field,
                         object freqstr=None, int month_kw=12):
     """
@@ -147,8 +150,8 @@ def get_start_end_field(int64_t[:] dtindex, object field,
         bint is_business = 0
         int end_month = 12
         int start_month = 1
-        ndarray[int8_t] out
-        ndarray[int32_t, ndim=2] _month_offset
+        int8_t[:] out
+        int32_t[:, :] _month_offset
         bint isleap
         npy_datetimestruct dts
         int mo_off, dom, doy, dow, ldom
@@ -163,8 +166,8 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
     if freqstr:
         if freqstr == 'C':
-            raise ValueError(
-                "Custom business days is not supported by %s" % field)
+            raise ValueError("Custom business days is not supported "
+                             "by {field}".format(field=field))
         is_business = freqstr[0] == 'B'
 
         # YearBegin(), BYearBegin() use month = starting month of year.
@@ -196,7 +199,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if (dom == 1 and dow < 5) or (dom <= 3 and dow == 0):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -208,7 +211,6 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if dom == 1:
                     out[i] = 1
-            return out.view(bool)
 
     elif field == 'is_month_end':
         if is_business:
@@ -228,7 +230,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
                 if (ldom == doy and dow < 5) or (
                         dow == 4 and (ldom - doy <= 2)):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -244,7 +246,6 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if ldom == doy:
                     out[i] = 1
-            return out.view(bool)
 
     elif field == 'is_quarter_start':
         if is_business:
@@ -260,7 +261,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
                 if ((dts.month - start_month) % 3 == 0) and (
                         (dom == 1 and dow < 5) or (dom <= 3 and dow == 0)):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -272,7 +273,6 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if ((dts.month - start_month) % 3 == 0) and dom == 1:
                     out[i] = 1
-            return out.view(bool)
 
     elif field == 'is_quarter_end':
         if is_business:
@@ -293,7 +293,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
                         (ldom == doy and dow < 5) or (
                             dow == 4 and (ldom - doy <= 2))):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -309,7 +309,6 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if ((dts.month - end_month) % 3 == 0) and (ldom == doy):
                     out[i] = 1
-            return out.view(bool)
 
     elif field == 'is_year_start':
         if is_business:
@@ -325,7 +324,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
                 if (dts.month == start_month) and (
                         (dom == 1 and dow < 5) or (dom <= 3 and dow == 0)):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -337,7 +336,6 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if (dts.month == start_month) and dom == 1:
                     out[i] = 1
-            return out.view(bool)
 
     elif field == 'is_year_end':
         if is_business:
@@ -358,7 +356,7 @@ def get_start_end_field(int64_t[:] dtindex, object field,
                         (ldom == doy and dow < 5) or (
                             dow == 4 and (ldom - doy <= 2))):
                     out[i] = 1
-            return out.view(bool)
+
         else:
             for i in range(count):
                 if dtindex[i] == NPY_NAT:
@@ -374,21 +372,23 @@ def get_start_end_field(int64_t[:] dtindex, object field,
 
                 if (dts.month == end_month) and (ldom == doy):
                     out[i] = 1
-            return out.view(bool)
 
-    raise ValueError("Field %s not supported" % field)
+    else:
+        raise ValueError("Field {field} not supported".format(field=field))
+
+    return np.asarray(out).view(bool)
 
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def get_date_field(ndarray[int64_t] dtindex, object field):
+def get_date_field(int64_t[:] dtindex, object field):
     """
     Given a int64-based datetime index, extract the year, month, etc.,
     field and return an array of these values.
     """
     cdef:
         Py_ssize_t i, count = 0
-        ndarray[int32_t] out
+        int32_t[:] out
         npy_datetimestruct dts
 
     count = len(dtindex)
@@ -403,7 +403,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.year
-        return out
 
     elif field == 'M':
         with nogil:
@@ -414,7 +413,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.month
-        return out
 
     elif field == 'D':
         with nogil:
@@ -425,7 +423,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.day
-        return out
 
     elif field == 'h':
         with nogil:
@@ -436,7 +433,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.hour
-        return out
 
     elif field == 'm':
         with nogil:
@@ -447,7 +443,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.min
-        return out
 
     elif field == 's':
         with nogil:
@@ -458,7 +453,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.sec
-        return out
 
     elif field == 'us':
         with nogil:
@@ -469,7 +463,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.us
-        return out
 
     elif field == 'ns':
         with nogil:
@@ -480,7 +473,7 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.ps / 1000
-        return out
+
     elif field == 'doy':
         with nogil:
             for i in range(count):
@@ -490,7 +483,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = get_day_of_year(dts.year, dts.month, dts.day)
-        return out
 
     elif field == 'dow':
         with nogil:
@@ -501,7 +493,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dayofweek(dts.year, dts.month, dts.day)
-        return out
 
     elif field == 'woy':
         with nogil:
@@ -512,7 +503,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = get_week_of_year(dts.year, dts.month, dts.day)
-        return out
 
     elif field == 'q':
         with nogil:
@@ -524,7 +514,6 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = dts.month
                 out[i] = ((out[i] - 1) / 3) + 1
-        return out
 
     elif field == 'dim':
         with nogil:
@@ -535,11 +524,14 @@ def get_date_field(ndarray[int64_t] dtindex, object field):
 
                 dt64_to_dtstruct(dtindex[i], &dts)
                 out[i] = get_days_in_month(dts.year, dts.month)
-        return out
+
     elif field == 'is_leap_year':
         return isleapyear_arr(get_date_field(dtindex, 'Y'))
 
-    raise ValueError("Field %s not supported" % field)
+    else:
+        raise ValueError("Field %s not supported" % field)
+
+    return np.asarray(out)
 
 
 @cython.wraparound(False)
@@ -551,7 +543,7 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
     """
     cdef:
         Py_ssize_t i, count = 0
-        ndarray[int32_t] out
+        int32_t[:] out
         pandas_timedeltastruct tds
 
     count = len(tdindex)
@@ -566,7 +558,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.days
-        return out
 
     elif field == 'h':
         with nogil:
@@ -577,7 +568,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.hrs
-        return out
 
     elif field == 's':
         with nogil:
@@ -588,7 +578,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.sec
-        return out
 
     elif field == 'seconds':
         with nogil:
@@ -599,7 +588,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.seconds
-        return out
 
     elif field == 'ms':
         with nogil:
@@ -610,7 +598,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.ms
-        return out
 
     elif field == 'microseconds':
         with nogil:
@@ -621,7 +608,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.microseconds
-        return out
 
     elif field == 'us':
         with nogil:
@@ -632,7 +618,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.us
-        return out
 
     elif field == 'ns':
         with nogil:
@@ -643,7 +628,6 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.ns
-        return out
 
     elif field == 'nanoseconds':
         with nogil:
@@ -654,9 +638,11 @@ def get_timedelta_field(int64_t[:] tdindex, object field):
 
                 td64_to_tdstruct(tdindex[i], &tds)
                 out[i] = tds.nanoseconds
-        return out
 
-    raise ValueError("Field %s not supported" % field)
+    else:
+        raise ValueError("Field {field} not supported".format(field=field))
+
+    return np.asarray(out)
 
 
 cpdef isleapyear_arr(ndarray years):
diff --git a/pandas/_libs/tslibs/offsets.pyx b/pandas/_libs/tslibs/offsets.pyx
index 528d30ddd7205..3af4107a333f8 100644
--- a/pandas/_libs/tslibs/offsets.pyx
+++ b/pandas/_libs/tslibs/offsets.pyx
@@ -816,7 +816,8 @@ def shift_months(int64_t[:] dtindex, int months, object day=None):
     return np.asarray(out)
 
 
-cpdef datetime shift_month(datetime stamp, int months, object day_opt=None):
+def shift_month(stamp: datetime, months: int,
+                day_opt: object = None) -> datetime:
     """
     Given a datetime (or Timestamp) `stamp`, an integer `months` and an
     option `day_opt`, return a new datetimelike that many months later,
@@ -946,8 +947,8 @@ cpdef int roll_convention(int other, int n, int compare) nogil:
     return n
 
 
-cpdef int roll_qtrday(datetime other, int n, int month, object day_opt,
-                      int modby=3) except? -1:
+def roll_qtrday(other: datetime, n: int, month: int,
+                day_opt: object, modby: int = 3) -> int:
     """
     Possibly increment or decrement the number of periods to shift
     based on rollforward/rollbackward conventions.
diff --git a/pandas/_libs/tslibs/period.pyx b/pandas/_libs/tslibs/period.pyx
index a769bbb081398..4eaeac66fda01 100644
--- a/pandas/_libs/tslibs/period.pyx
+++ b/pandas/_libs/tslibs/period.pyx
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# cython: boundscheck=False, wraparound=False
 from datetime import datetime, date
 
 from cpython cimport (
@@ -1002,7 +1003,7 @@ def dt64arr_to_periodarr(int64_t[:] dtarr, int freq, tz=None):
                 out[i] = get_period_ordinal(&dts, freq)
     else:
         out = localize_dt64arr_to_period(dtarr, freq, tz)
-    return out.base  # .base to access underlying np.ndarray
+    return np.asarray(out)
 
 
 @cython.wraparound(False)
@@ -1027,7 +1028,7 @@ def periodarr_to_dt64arr(int64_t[:] periodarr, int freq):
                 continue
             out[i] = period_ordinal_to_dt64(periodarr[i], freq)
 
-    return out.base  # .base to access underlying np.ndarray
+    return np.asarray(out)
 
 
 cpdef int64_t period_asfreq(int64_t ordinal, int freq1, int freq2, bint end):
@@ -1107,7 +1108,7 @@ cdef inline int calc_week_end(int freq, int group) nogil:
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def period_asfreq_arr(ndarray[int64_t] arr, int freq1, int freq2, bint end):
+def period_asfreq_arr(int64_t[:] arr, int freq1, int freq2, bint end):
     """
     Convert int64-array of period ordinals from one frequency to another, and
     if upsampling, choose to use start ('S') or end ('E') of period.
@@ -1125,23 +1126,15 @@ def period_asfreq_arr(ndarray[int64_t] arr, int freq1, int freq2, bint end):
     func = get_asfreq_func(freq1, freq2)
     get_asfreq_info(freq1, freq2, end, &af_info)
 
-    mask = arr == NPY_NAT
-    if mask.any():      # NaT process
-        for i in range(n):
-            val = arr[i]
-            if val != NPY_NAT:
-                val = func(val, &af_info)
-                if val == INT32_MIN:
-                    raise ValueError("Unable to convert to desired frequency.")
-            result[i] = val
-    else:
-        for i in range(n):
-            val = func(arr[i], &af_info)
+    for i in range(n):
+        val = arr[i]
+        if val != NPY_NAT:
+            val = func(val, &af_info)
             if val == INT32_MIN:
                 raise ValueError("Unable to convert to desired frequency.")
-            result[i] = val
+        result[i] = val
 
-    return result.base  # .base to access underlying np.ndarray
+    return np.asarray(result)
 
 
 cpdef int64_t period_ordinal(int y, int m, int d, int h, int min,
@@ -1240,6 +1233,7 @@ cdef list extra_fmts = [(b"%q", b"^`AB`^"),
 cdef list str_extra_fmts = ["^`AB`^", "^`CD`^", "^`EF`^",
                             "^`GH`^", "^`IJ`^", "^`KL`^"]
 
+
 cdef object _period_strftime(int64_t value, int freq, object fmt):
     cdef:
         Py_ssize_t i
@@ -1403,7 +1397,7 @@ def get_period_field_arr(int code, int64_t[:] arr, int freq):
             continue
         out[i] = func(arr[i], freq)
 
-    return out.base  # .base to access underlying np.ndarray
+    return np.asarray(out)
 
 
 cdef accessor _get_accessor_func(int code):
@@ -1465,7 +1459,7 @@ def extract_ordinals(object[:] values, freq):
                 else:
                     ordinals[i] = p.ordinal
 
-    return ordinals.base  # .base to access underlying np.ndarray
+    return np.asarray(ordinals)
 
 
 def extract_freq(object[:] values):
diff --git a/pandas/_libs/tslibs/timedeltas.pyx b/pandas/_libs/tslibs/timedeltas.pyx
index 74bbc64af25f2..75394f0794708 100644
--- a/pandas/_libs/tslibs/timedeltas.pyx
+++ b/pandas/_libs/tslibs/timedeltas.pyx
@@ -6,6 +6,7 @@ import warnings
 import sys
 cdef bint PY3 = (sys.version_info[0] >= 3)
 
+import cython
 from cython import Py_ssize_t
 
 from cpython cimport Py_NE, Py_EQ, PyObject_RichCompare
@@ -82,7 +83,9 @@ _no_input = object()
 # ----------------------------------------------------------------------
 # API
 
-def ints_to_pytimedelta(int64_t[:] arr, box=False):
+@cython.boundscheck(False)
+@cython.wraparound(False)
+def ints_to_pytimedelta(int64_t[:] arr, bint box=False):
     """
     convert an i8 repr to an ndarray of timedelta or Timedelta (if box ==
     True)
@@ -198,6 +201,8 @@ cpdef convert_to_timedelta64(object ts, object unit):
     return ts.astype('timedelta64[ns]')
 
 
+@cython.boundscheck(False)
+@cython.wraparound(False)
 def array_to_timedelta64(object[:] values, unit='ns', errors='raise'):
     """
     Convert an ndarray to an array of timedeltas. If errors == 'coerce',
diff --git a/pandas/_libs/tslibs/timestamps.pyx b/pandas/_libs/tslibs/timestamps.pyx
index 65da765bae739..73a59d75cae2a 100644
--- a/pandas/_libs/tslibs/timestamps.pyx
+++ b/pandas/_libs/tslibs/timestamps.pyx
@@ -968,49 +968,49 @@ class Timestamp(_Timestamp):
         return getattr(self.freq, 'freqstr', self.freq)
 
     @property
-    def is_month_start(self):
+    def is_month_start(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return self.day == 1
         return self._get_start_end_field('is_month_start')
 
     @property
-    def is_month_end(self):
+    def is_month_end(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return self.day == self.days_in_month
         return self._get_start_end_field('is_month_end')
 
     @property
-    def is_quarter_start(self):
+    def is_quarter_start(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return self.day == 1 and self.month % 3 == 1
         return self._get_start_end_field('is_quarter_start')
 
     @property
-    def is_quarter_end(self):
+    def is_quarter_end(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return (self.month % 3) == 0 and self.day == self.days_in_month
         return self._get_start_end_field('is_quarter_end')
 
     @property
-    def is_year_start(self):
+    def is_year_start(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return self.day == self.month == 1
         return self._get_start_end_field('is_year_start')
 
     @property
-    def is_year_end(self):
+    def is_year_end(self) -> bool:
         if self.freq is None:
             # fast-path for non-business frequencies
             return self.month == 12 and self.day == 31
         return self._get_start_end_field('is_year_end')
 
     @property
-    def is_leap_year(self):
+    def is_leap_year(self) -> bool:
         return bool(ccalendar.is_leapyear(self.year))
 
     def tz_localize(self, tz, ambiguous='raise', nonexistent='raise',