diff --git a/web/services/city_api.py b/web/services/city_api.py
index 0d6d24af..141d05a3 100644
--- a/web/services/city_api.py
+++ b/web/services/city_api.py
@@ -20,6 +20,7 @@ from web.services.canonical_temperature import build_city_weather_from_canonical
 from web.services.latest_observation_overlay import (
     overlay_latest_amos_observation,
     overlay_latest_amsc_observation,
+    overlay_latest_hko_observation,
     overlay_latest_jma_amedas_observation,
     overlay_latest_mgm_observation,
     parse_observation_epoch,
@@ -687,6 +688,13 @@ async def _get_city_chart_data(city: str, *, force_refresh: bool) -> Dict[str, A
             fn=overlay_latest_mgm_observation,
             args=(legacy_routes._CACHE_DB, city, payload),
         )
+        payload = await _run_optional_city_chart_overlay(
+            city=city,
+            overlay_name="hko_latest_raw",
+            payload=payload,
+            fn=overlay_latest_hko_observation,
+            args=(legacy_routes._CACHE_DB, city, payload),
+        )
         return await _run_optional_city_chart_overlay(
             city=city,
             overlay_name="wunderground_current",
@@ -737,6 +745,13 @@ async def _get_city_chart_data(city: str, *, force_refresh: bool) -> Dict[str, A
                 fn=overlay_latest_mgm_observation,
                 args=(legacy_routes._CACHE_DB, city, payload),
             )
+            payload = await _run_optional_city_chart_overlay(
+                city=city,
+                overlay_name="hko_latest_raw",
+                payload=payload,
+                fn=overlay_latest_hko_observation,
+                args=(legacy_routes._CACHE_DB, city, payload),
+            )
             return await _run_optional_city_chart_overlay(
                 city=city,
                 overlay_name="wunderground_current",
diff --git a/web/services/latest_observation_overlay.py b/web/services/latest_observation_overlay.py
index 4c581fa3..e92faa5b 100644
--- a/web/services/latest_observation_overlay.py
+++ b/web/services/latest_observation_overlay.py
@@ -793,7 +793,79 @@ def overlay_latest_amos_observation(db, city, payload):
 
 
 # ═══════════════════════════════════════════════════════════════════════════════
-# MGM (Turkish State Meteorological Service — Ankara, Istanbul)
+# HKO (Hong Kong Observatory — Hong Kong, Shenzhen)
+# ═══════════════════════════════════════════════════════════════════════════════
+
+
+def _latest_hko_row(db, city):
+    getter = getattr(db, "get_latest_raw_observation", None)
+    if not callable(getter):
+        return None, None
+    try:
+        row = getter("hko_obs", city)
+    except Exception as exc:
+        logger.debug("latest HKO raw overlay read failed city={}: {}", city, exc)
+        return None, None
+    if not isinstance(row, dict):
+        return None, None
+    raw_payload = row.get("payload")
+    if isinstance(raw_payload, dict) and raw_payload:
+        temp = raw_payload.get("temp")
+        if temp is not None:
+            return row, raw_payload
+    return None, None
+
+
+def _raw_hko_epoch(row, raw_payload):
+    payload_values = (raw_payload.get("obs_time"),)
+    parsed = [
+        epoch
+        for epoch in (parse_observation_epoch(value) for value in payload_values)
+        if epoch is not None
+    ]
+    if parsed:
+        return max(parsed)
+    return parse_observation_epoch(row.get("observed_at"))
+
+
+def overlay_latest_hko_observation(db, city, payload):
+    normalized_city = str(city or payload.get("name") or payload.get("city") or "").strip().lower()
+    if not normalized_city or not isinstance(payload, dict) or not payload:
+        return payload
+    row, raw_payload = _latest_hko_row(db, normalized_city)
+    if not isinstance(row, dict) or not isinstance(raw_payload, dict):
+        return payload
+    raw_epoch = _raw_hko_epoch(row, raw_payload)
+    if raw_epoch is None:
+        return payload
+    update = _raw_observation_update(normalized_city, row, raw_payload)
+    if not update:
+        return payload
+
+    next_payload = deepcopy(payload)
+    changed = False
+
+    for key in ("current", "airport_primary", "airport_current"):
+        changed = _merge_observation_block(next_payload, key, update, raw_epoch) or changed
+
+    canonical = next_payload.get("canonical_temperature")
+    canonical_epoch = _block_epoch(canonical)
+    if canonical_epoch is None or raw_epoch > canonical_epoch:
+        canonical_payload = build_canonical_temperature(
+            normalized_city,
+            {
+                "name": normalized_city,
+                "temp_symbol": next_payload.get("temp_symbol") or "\u00b0C",
+                "updated_at": row.get("fetched_at"),
+                "current": update,
+            },
+            fetched_at=str(row.get("fetched_at") or ""),
+        )
+        if canonical_payload:
+            next_payload["canonical_temperature"] = canonical_payload
+            changed = True
+
+    return next_payload if changed else payload
 # ═══════════════════════════════════════════════════════════════════════════════