diff --git a/src/pygui/backend/controllers/session_controller.py b/src/pygui/backend/controllers/session_controller.py
index 0288f6a..a327c44 100644
--- a/src/pygui/backend/controllers/session_controller.py
+++ b/src/pygui/backend/controllers/session_controller.py
@@ -11,6 +11,7 @@ from pygui.backend.cluster_average import average_clusters, group_sensors_by_rad
 from pygui.backend.data.csv_recorder import CsvRecorder
 from pygui.backend.models.frame import Frame
 from pygui.backend.models.frame_player import FramePlayer, frames_from_wafer_data
+from pygui.backend.models.replay_stats import ReplayStatsTracker
 from pygui.backend.models.sensor_editor import SensorEditor
 from pygui.backend.models.session_model import SessionModel
 from pygui.backend.models.threshold_classifier import ThresholdConfig
@@ -34,6 +35,8 @@ class SessionController(QObject):
     sensorsChanged = Signal()
     loadedFileChanged = Signal()
     clusterAveragingEnabledChanged = Signal()
+    # trend: per-frame avg for live graph
+    trendData = Signal(str)  # JSON array of floats
     # private: marshal a worker-thread frame onto the main thread
     _liveFrame = Signal(object)    # Frame
 
@@ -65,6 +68,7 @@ class SessionController(QObject):
         self._loaded_file: str = ""
         self._cluster_averaging_enabled = False
         self._active_clusters: list[list[int]] = []
+        self._stats_tracker = ReplayStatsTracker()
 
     # ---- properties QML binds to ----
     @Property(str, notify=modeChanged)
@@ -248,6 +252,7 @@ class SessionController(QObject):
             self._active_clusters = group_sensors_by_radius(self._sensors)
         self._player.load(frames)
         self._model.reset()
+        self._stats_tracker.reset()
         self._loaded_file = file_path
         self.loadedFileChanged.emit()
         self.sensorsChanged.emit()
@@ -378,6 +383,7 @@ class SessionController(QObject):
 
         # Clear out any old data from the prev sessions
         self._model.reset()
+        self._stats_tracker.reset()
         self._last = None
         self._last_raw_frame = None
 
@@ -424,6 +430,8 @@ class SessionController(QObject):
     @Slot(object)
     @slot_error_boundary
     def _on_live_frame(self, frame: Frame) -> None:
+        import json
+        self._stats_tracker.track(frame.seq, frame.values)
         # Main thread (queued). Record raw, process edited; mark dirty for repaint.
         self._last_raw_frame = frame
         edited = Frame(seq=frame.seq, time=frame.time,
@@ -432,6 +440,7 @@ class SessionController(QObject):
         if self._recorder.is_recording:
             self._recorder.write(frame)   # always record raw values, never edited
         self._dirty = True
+        self.trendData.emit(json.dumps(self._stats_tracker.get_trend()))
 
     def _flush_repaint(self) -> None:
         if not self._dirty:
diff --git a/src/pygui/backend/models/replay_stats.py b/src/pygui/backend/models/replay_stats.py
new file mode 100644
index 0000000..7794b6e
--- /dev/null
+++ b/src/pygui/backend/models/replay_stats.py
@@ -0,0 +1,37 @@
+import numpy as np
+
+
+class ReplayStatsTracker:
+    """Accumulates per-frames statistic acrossa replay session."""
+
+    def __init__(self) -> None:
+        self.history: list[dict] = []
+        self.running_avg: float = 0.0
+
+    def track(self, frame_index: int, temperatures: list[float]) -> dict:
+        arr = np.array(temperatures, dtype = np.float32)
+        clean_arr = arr[np.isfinite(arr)]
+
+        if clean_arr.size == 0:
+            stats = {"frame": frame_index, "min":0.0, "max":0.0, "avg":0.0, "std":0.0}
+        else:
+            stats = {
+                "frame": frame_index,
+                "min": float(np.min(clean_arr)),
+                "max": float(np.max(clean_arr)),
+                "avg": float(np.mean(clean_arr)),
+                "std": float(np.std(clean_arr)),
+            }
+
+        self.history.append(stats)
+        if self.history:
+            self.running_avg = float(np.mean([s["avg"] for s in self.history]))
+        return stats
+
+    def get_trend(self) -> list[float]:
+        """Return list of per-frame average for trend chat"""
+        return [s["avg"] for s in self.history]
+
+    def reset(self) -> None:
+        self.history.clear()
+        self.running_avg = 0.0
diff --git a/src/pygui/backend/visualization/graph_view.py b/src/pygui/backend/visualization/graph_view.py
index 1a3d7ba..874fe38 100644
--- a/src/pygui/backend/visualization/graph_view.py
+++ b/src/pygui/backend/visualization/graph_view.py
@@ -164,3 +164,30 @@ class GraphView(QObject):
             self._plot_window = None
             self._plot_widget = None
             self._series = []
+
+    @Slot(str)
+    def updateTrend(self, avgs_json: str) -> None:
+        """Plot the running avg temp series."""
+        import json
+        if not self._plot_widget:
+            return
+        try:
+            avgs = json.loads(avgs_json)
+        except (json.JSONDecodeError, TypeError) as exc:
+                log.error("Failed to parse trend data: %s", exc)
+                return
+
+        if hasattr(self,'_trend_line') and self._trend_line is not None:
+            self._plot_widget.removeItem(self._trend_line)
+
+        if not avgs:
+            return
+
+        x = list(range(len(avgs)))
+        pen = pg.mkPen("#5B9DF5", width=2)
+        self._trend_line = self._plot_widget.plot(x, avgs, name="Average", pen=pen)
+
+        # Y-axis range with buffer
+        y_min, y_max = min(avgs), max(avgs)
+        buf = max((y_max - y_min) * 0.1, 1.0) if y_max > y_min else 5.0
+        self._plot_widget.setYRange(y_min - buf, y_max + buf)