diff --git a/aodh/evaluator/threshold.py b/aodh/evaluator/threshold.py
index 885e23692..20516b362 100644
--- a/aodh/evaluator/threshold.py
+++ b/aodh/evaluator/threshold.py
@@ -19,6 +19,7 @@ import operator
 import six
 
 from ceilometerclient import client as ceiloclient
+from oslo_config import cfg
 from oslo_log import log
 from oslo_utils import timeutils
 
@@ -38,11 +39,20 @@ COMPARATORS = {
     'ne': operator.ne,
 }
 
+OPTS = [
+    cfg.IntOpt('additional_ingestion_lag',
+               min=0,
+               default=0,
+               help='The number of seconds to extend the evaluation windows '
+               'to compensate the reporting/ingestion lag.')
+]
+
 
 class ThresholdEvaluator(evaluator.Evaluator):
 
     # the sliding evaluation window is extended to allow
-    # for reporting/ingestion lag
+    # the reporting/ingestion lag this can be increased
+    # with 'additional_ingestion_lag' seconds if needed.
     look_back = 1
 
     def __init__(self, conf):
@@ -63,17 +73,17 @@ class ThresholdEvaluator(evaluator.Evaluator):
 
         return self._cm_client
 
-    @classmethod
-    def _bound_duration(cls, rule):
+    def _bound_duration(self, rule):
         """Bound the duration of the statistics query."""
         now = timeutils.utcnow()
         # when exclusion of weak datapoints is enabled, we extend
         # the look-back period so as to allow a clearer sample count
         # trend to be established
-        look_back = (cls.look_back if not rule.get('exclude_outliers')
+        look_back = (self.look_back if not rule.get('exclude_outliers')
                      else rule['evaluation_periods'])
         window = ((rule.get('period', None) or rule['granularity'])
-                  * (rule['evaluation_periods'] + look_back))
+                  * (rule['evaluation_periods'] + look_back) +
+                  self.conf.additional_ingestion_lag)
         start = now - datetime.timedelta(seconds=window)
         LOG.debug('query stats from %(start)s to '
                   '%(now)s', {'start': start, 'now': now})
diff --git a/aodh/opts.py b/aodh/opts.py
index cec31eeae..dbc02f2d1 100644
--- a/aodh/opts.py
+++ b/aodh/opts.py
@@ -35,6 +35,7 @@ def list_opts():
          itertools.chain(
              aodh.evaluator.OPTS,
              aodh.evaluator.event.OPTS,
+             aodh.evaluator.threshold.OPTS,
              aodh.notifier.rest.OPTS,
              aodh.queue.OPTS,
              aodh.service.OPTS)),
diff --git a/aodh/tests/unit/evaluator/test_threshold.py b/aodh/tests/unit/evaluator/test_threshold.py
index 30b5f7e90..1134215b0 100644
--- a/aodh/tests/unit/evaluator/test_threshold.py
+++ b/aodh/tests/unit/evaluator/test_threshold.py
@@ -193,6 +193,56 @@ class TestEvaluate(base.TestEvaluatorBase):
                     in zip(self.alarms, reasons, reason_datas)]
         self.assertEqual(expected, self.notifier.notify.call_args_list)
 
+    @mock.patch.object(timeutils, 'utcnow')
+    def test_lag_configuration(self, mock_utcnow):
+        mock_utcnow.return_value = datetime.datetime(2012, 7, 2, 10, 45)
+        self.api_client.statistics.list.side_effect = []
+
+        self._set_all_alarms('ok')
+        self._evaluate_all_alarms()
+        self._set_all_alarms('ok')
+        self.conf.set_override("additional_ingestion_lag", 42)
+        self._evaluate_all_alarms()
+
+        self.assertEqual([
+            mock.call(
+                meter_name='cpu_util', period=60,
+                q=[{'value': 'cpu_util', 'op': 'eq', 'field': 'meter'},
+                   {'value': 'my_instance', 'op': 'eq',
+                    'field': 'resource_id'},
+                   {'value': '2012-07-02T10:45:00', 'op': 'le',
+                    'field': 'timestamp'},
+                   {'value': '2012-07-02T10:39:00', 'op': 'ge',
+                    'field': 'timestamp'}]),
+            mock.call(
+                meter_name='cpu_util', period=300,
+                q=[{'value': 'cpu_util', 'op': 'eq', 'field': 'meter'},
+                   {'value': 'my_group', 'op': 'eq',
+                    'field': 'metadata.user_metadata.AS'},
+                   {'value': '2012-07-02T10:45:00', 'op': 'le',
+                    'field': 'timestamp'},
+                   {'value': '2012-07-02T10:20:00', 'op': 'ge',
+                    'field': 'timestamp'}]),
+            mock.call(
+                meter_name='cpu_util', period=60,
+                q=[{'value': 'cpu_util', 'op': 'eq', 'field': 'meter'},
+                   {'value': 'my_instance', 'op': 'eq',
+                    'field': 'resource_id'},
+                   {'value': '2012-07-02T10:45:00', 'op': 'le',
+                    'field': 'timestamp'},
+                   {'value': '2012-07-02T10:38:18', 'op': 'ge',
+                    'field': 'timestamp'}]),
+            mock.call(
+                meter_name='cpu_util', period=300,
+                q=[{'value': 'cpu_util', 'op': 'eq', 'field': 'meter'},
+                   {'value': 'my_group', 'op': 'eq',
+                    'field': 'metadata.user_metadata.AS'},
+                   {'value': '2012-07-02T10:45:00', 'op': 'le',
+                    'field': 'timestamp'},
+                   {'value': '2012-07-02T10:19:18', 'op': 'ge',
+                    'field': 'timestamp'}])],
+            self.api_client.statistics.list.mock_calls)
+
     def test_simple_alarm_clear(self):
         self._set_all_alarms('alarm')
         avgs = [self._get_stat('avg', self.alarms[0].rule['threshold'] - v)
diff --git a/releasenotes/notes/ingestion-lag-2317725887287fbc.yaml b/releasenotes/notes/ingestion-lag-2317725887287fbc.yaml
new file mode 100644
index 000000000..dc2b52c19
--- /dev/null
+++ b/releasenotes/notes/ingestion-lag-2317725887287fbc.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - Allow to extends the alarm evaluation windows to to compensate the
+    reporting/ingestion lag.
+
+    An new option is introduced additional_ingestion_lag defaulted to 0.
+    It represents the number of seconds of the window extension.