diff --git a/airflow/operators/sensors.py b/airflow/operators/sensors.py
index 2062937b7b..86af970986 100644
--- a/airflow/operators/sensors.py
+++ b/airflow/operators/sensors.py
@@ -36,7 +36,7 @@ class BaseSensorOperator(BaseOperator):
         self.poke_interval = poke_interval
         self.timeout = timeout
 
-    def poke(self):
+    def poke(self, context):
         '''
         Function that the sensors defined while deriving this class should
         override.
@@ -45,7 +45,7 @@ class BaseSensorOperator(BaseOperator):
 
     def execute(self, context):
         started_at = datetime.now()
-        while not self.poke():
+        while not self.poke(context):
             sleep(self.poke_interval)
             if (datetime.now() - started_at).seconds > self.timeout:
                 raise AirflowException('Snap. Time is OUT.')
@@ -81,7 +81,7 @@ class SqlSensor(BaseSensorOperator):
         session.commit()
         session.close()
 
-    def poke(self):
+    def poke(self, context):
         logging.info('Poking: ' + self.sql)
         records = self.hook.get_records(self.sql)
         if not records:
@@ -105,30 +105,26 @@ class ExternalTaskSensor(BaseSensorOperator):
         wait for
     :type external_task_id: string
     """
-    template_fields = ('execution_date',)
 
     @apply_defaults
     def __init__(self, external_dag_id, external_task_id, *args, **kwargs):
         super(ExternalTaskSensor, self).__init__(*args, **kwargs)
         self.external_dag_id = external_dag_id
         self.external_task_id = external_task_id
-        self.execution_date = "{{ execution_date }}"
 
-    def poke(self):
+    def poke(self, context):
         logging.info(
             'Poking for '
             '{self.external_dag_id}.'
             '{self.external_task_id} on '
-            '{self.execution_date} ... '.format(**locals()))
+            '{context[execution_date]} ... '.format(**locals()))
         TI = TaskInstance
         session = settings.Session()
-        import dateutil.parser
-        self.execution_date = dateutil.parser.parse(self.execution_date)
         count = session.query(TI).filter(
             TI.dag_id == self.external_dag_id,
             TI.task_id == self.external_task_id,
             TI.state == State.SUCCESS,
-            TI.execution_date == self.execution_date
+            TI.execution_date == context['execution_date'],
         ).count()
         session.commit()
         session.close()
@@ -169,7 +165,7 @@ class HivePartitionSensor(BaseSensorOperator):
         self.partition = partition
         self.schema = schema
 
-    def poke(self):
+    def poke(self, context):
         logging.info(
             'Poking for table {self.schema}.{self.table}, '
             'partition {self.partition}'.format(**locals()))
@@ -196,7 +192,7 @@ class HdfsSensor(BaseSensorOperator):
         self.filepath = filepath
         self.hdfs_conn_id = hdfs_conn_id
 
-    def poke(self):
+    def poke(self, context):
         sb = hooks.HDFSHook(self.hdfs_conn_id).get_conn()
         logging.getLogger("snakebite").setLevel(logging.WARNING)
         logging.info(
@@ -255,7 +251,7 @@ class S3KeySensor(BaseSensorOperator):
         session.commit()
         session.close()
 
-    def poke(self):
+    def poke(self, context):
         hook = hooks.S3Hook(s3_conn_id=self.s3_conn_id)
         full_url = "s3://" + self.bucket_name + self.bucket_key
         logging.info('Poking for key : {full_url}'.format(**locals()))
@@ -307,7 +303,7 @@ class S3PrefixSensor(BaseSensorOperator):
         session.commit()
         session.close()
 
-    def poke(self):
+    def poke(self, context):
         logging.info('Poking for prefix : {self.prefix}\n'
                      'in bucket s3://{self.bucket_name}'.format(**locals()))
         hook = hooks.S3Hook(s3_conn_id=self.s3_conn_id)
@@ -331,7 +327,7 @@ class TimeSensor(BaseSensorOperator):
         super(TimeSensor, self).__init__(*args, **kwargs)
         self.target_time = target_time
 
-    def poke(self):
+    def poke(self, context):
         logging.info(
             'Checking if the time ({0}) has come'.format(self.target_time))
         return datetime.now().time() > self.target_time