diff --git a/arrow/arrow.py b/arrow/arrow.py
index f0a57f04..3f8ab751 100644
--- a/arrow/arrow.py
+++ b/arrow/arrow.py
@@ -1245,6 +1245,9 @@ def humanize(
                     weeks = sign * max(delta_second // self._SECS_PER_WEEK, 2)
                     return locale.describe("weeks", weeks, only_distance=only_distance)
 
+                elif calendar_months < 1 and diff >= self._SECS_PER_MONTH:
+                    return locale.describe("month", sign, only_distance=only_distance)
+
                 elif calendar_months >= 1 and diff < self._SECS_PER_YEAR:
                     if calendar_months == 1:
                         return locale.describe(
diff --git a/tests/test_arrow.py b/tests/test_arrow.py
index b595e4e2..69ba1db6 100644
--- a/tests/test_arrow.py
+++ b/tests/test_arrow.py
@@ -2223,6 +2223,14 @@ def test_month(self):
         assert self.now.humanize(later, only_distance=True) == "a month"
         assert later.humanize(self.now, only_distance=True) == "a month"
 
+    def test_month_boundary_with_large_delta(self):
+        """~31 days where calendar_months is 0 but elapsed exceeds _SECS_PER_MONTH."""
+        # Jan 15 -> Feb 15: calendar_months may round to 0, but 31 days > 30.5
+        arw = arrow.Arrow(2013, 1, 15)
+        later = arrow.Arrow(2013, 2, 15)
+        assert arw.humanize(later) == "a month ago"
+        assert later.humanize(arw) == "in a month"
+
     def test_months(self):
         later = self.now.shift(months=2)
         earlier = self.now.shift(months=-2)