diff --git a/backend/scripts/wipe-samples.ts b/backend/scripts/wipe-samples.ts
new file mode 100644
index 0000000..3245651
--- /dev/null
+++ b/backend/scripts/wipe-samples.ts
@@ -0,0 +1,26 @@
+/**
+ * One-off cleanup: wipe ride history accumulated before the operating-window
+ * gate was added to the sampler. Safe to re-run; truncates only the two
+ * sample-related tables, leaves park_days untouched.
+ */
+import Database from "better-sqlite3";
+import path from "path";
+
+const dbPath = path.join(__dirname, "..", "data", "parks.db");
+const db = new Database(dbPath);
+
+const before = {
+  samples: (db.prepare("SELECT COUNT(*) AS c FROM ride_wait_samples").get() as { c: number }).c,
+  rides: (db.prepare("SELECT COUNT(*) AS c FROM rides").get() as { c: number }).c,
+};
+console.log("Before:", before);
+
+db.exec("DELETE FROM ride_wait_samples; DELETE FROM rides;");
+
+const after = {
+  samples: (db.prepare("SELECT COUNT(*) AS c FROM ride_wait_samples").get() as { c: number }).c,
+  rides: (db.prepare("SELECT COUNT(*) AS c FROM rides").get() as { c: number }).c,
+};
+console.log("After: ", after);
+
+db.close();
diff --git a/backend/src/services/wait-sampler.ts b/backend/src/services/wait-sampler.ts
index 169383d..858cf0b 100644
--- a/backend/src/services/wait-sampler.ts
+++ b/backend/src/services/wait-sampler.ts
@@ -23,6 +23,7 @@ import { fetchLiveRides } from "../../../lib/scrapers/queuetimes";
 import { fetchFastLaneWaits, lookupFastLane } from "../../../lib/scrapers/sixflags-waittimes";
 import { slugifyRideName } from "../../../lib/ride-slug";
 import { formatLocalDate, formatLocalTime } from "../../../lib/timezone";
+import { isWithinOperatingWindow } from "../../../lib/env";
 import { liveRidesCache, fastLaneCache } from "./live-cache";
 import { getDayData, upsertRide, insertSample, transact } from "../db/queries";
 
@@ -133,10 +134,15 @@ export async function sampleAllOpenParks(): Promise<SampleRunResult> {
     errors: 0,
   };
 
-  // Filter to parks open today.
+  // Filter to parks that are open today AND currently within their operating
+  // window. Queue-Times keeps reporting yesterday's last wait with isOpen=true
+  // overnight, so the per-ride open check isn't enough on its own — we'd
+  // otherwise pollute uptime stats with phantom open samples between close
+  // and the next morning's first refresh.
   const openParks = PARKS.filter((park) => {
     const day = getDayData(park.id, today);
-    return day?.isOpen ?? false;
+    if (!day?.isOpen || !day.hoursLabel) return false;
+    return isWithinOperatingWindow(day.hoursLabel, park.timezone);
   });
   result.parksSkipped = PARKS.length - openParks.length;