diff --git a/backend/open_webui/models/calendar.py b/backend/open_webui/models/calendar.py
index 48b28d8e9a..75ccfcab1c 100644
--- a/backend/open_webui/models/calendar.py
+++ b/backend/open_webui/models/calendar.py
@@ -696,6 +696,7 @@ class CalendarEventTable:
         self,
         now_ns: int,
         default_lookahead_ns: int,
+        grace_ns: int = 0,
         db: Optional[AsyncSession] = None,
     ) -> list[tuple[CalendarEventModel, Optional[str]]]:
         """Events starting between now and now + lookahead, for alert processing.
@@ -716,7 +717,7 @@ class CalendarEventTable:
                 .outerjoin(UserRow, UserRow.id == CalendarEvent.user_id)
                 .filter(
                     CalendarEvent.is_cancelled == False,
-                    CalendarEvent.start_at >= now_ns,
+                    CalendarEvent.start_at >= now_ns - grace_ns,
                     CalendarEvent.start_at <= upper,
                 )
             )
diff --git a/backend/open_webui/utils/automations.py b/backend/open_webui/utils/automations.py
index 05955d54d9..bb72a999b5 100644
--- a/backend/open_webui/utils/automations.py
+++ b/backend/open_webui/utils/automations.py
@@ -501,9 +501,10 @@ async def _check_calendar_alerts(app) -> None:
 
     now_ns = int(time.time_ns())
     default_lookahead_ns = CALENDAR_ALERT_LOOKAHEAD_MINUTES * 60 * 1_000_000_000
+    grace_ns = SCHEDULER_POLL_INTERVAL * 1_000_000_000
 
     async with get_async_db() as db:
-        upcoming = await CalendarEvents.get_upcoming_events(now_ns, default_lookahead_ns, db=db)
+        upcoming = await CalendarEvents.get_upcoming_events(now_ns, default_lookahead_ns,grace_ns=grace_ns, db=db)
 
     if not upcoming:
         return