diff --git a/packages/tinybird/endpoints/endpoint__dns_status_15m__v0.pipe b/packages/tinybird/endpoints/endpoint__dns_status_15m__v0.pipe
index af35a85b7..ce72f612b 100644
--- a/packages/tinybird/endpoints/endpoint__dns_status_15m__v0.pipe
+++ b/packages/tinybird/endpoints/endpoint__dns_status_15m__v0.pipe
@@ -2,9 +2,10 @@ NODE endpoint
 SQL >
 
 %
+WITH {{ String(timezone, 'UTC') }} AS tz
 SELECT
     -- calendar date of the local day; the client re-keys it as UTC midnight like the 45d pipes
-    toDate(toTimeZone(time, {{ String(timezone, 'UTC') }})) AS day,
+    toDate(toTimeZone(time, tz)) AS day,
     monitorId,
     countMerge(count) AS count,
     countMerge(success) AS ok,
@@ -12,6 +13,9 @@ SELECT
     countMerge(degraded) AS degraded
 FROM mv__dns_status_15m__v0
 WHERE monitorId IN {{ Array(monitorIds, 'String', '1,666') }}
+    -- start at a local midnight so the oldest day is complete, not cut at the
+    -- 46-day TTL edge; stays inside the TTL for every zone (at most 45d + 14h)
+    AND time >= toStartOfDay(toTimeZone(now(), tz)) - INTERVAL 45 DAY
 GROUP BY day, monitorId
 ORDER BY day DESC
 
diff --git a/packages/tinybird/endpoints/endpoint__grpc_status_15m__v0.pipe b/packages/tinybird/endpoints/endpoint__grpc_status_15m__v0.pipe
index cb1b0332f..cb821e87c 100644
--- a/packages/tinybird/endpoints/endpoint__grpc_status_15m__v0.pipe
+++ b/packages/tinybird/endpoints/endpoint__grpc_status_15m__v0.pipe
@@ -2,9 +2,10 @@ NODE endpoint
 SQL >
 
 %
+WITH {{ String(timezone, 'UTC') }} AS tz
 SELECT
     -- calendar date of the local day; the client re-keys it as UTC midnight like the 45d pipes
-    toDate(toTimeZone(time, {{ String(timezone, 'UTC') }})) AS day,
+    toDate(toTimeZone(time, tz)) AS day,
     monitorId,
     countMerge(count) AS count,
     countMerge(success) AS ok,
@@ -12,6 +13,9 @@ SELECT
     countMerge(degraded) AS degraded
 FROM mv__grpc_status_15m__v0
 WHERE monitorId IN {{ Array(monitorIds, 'String', '1,666') }}
+    -- start at a local midnight so the oldest day is complete, not cut at the
+    -- 46-day TTL edge; stays inside the TTL for every zone (at most 45d + 14h)
+    AND time >= toStartOfDay(toTimeZone(now(), tz)) - INTERVAL 45 DAY
 GROUP BY day, monitorId
 ORDER BY day DESC
 
diff --git a/packages/tinybird/endpoints/endpoint__http_status_15m__v0.pipe b/packages/tinybird/endpoints/endpoint__http_status_15m__v0.pipe
index 18a10cd0b..54fc7e8b2 100644
--- a/packages/tinybird/endpoints/endpoint__http_status_15m__v0.pipe
+++ b/packages/tinybird/endpoints/endpoint__http_status_15m__v0.pipe
@@ -2,9 +2,10 @@ NODE endpoint
 SQL >
 
 %
+WITH {{ String(timezone, 'UTC') }} AS tz
 SELECT
     -- calendar date of the local day; the client re-keys it as UTC midnight like the 45d pipes
-    toDate(toTimeZone(time, {{ String(timezone, 'UTC') }})) AS day,
+    toDate(toTimeZone(time, tz)) AS day,
     monitorId,
     countMerge(count) AS count,
     countMerge(success) AS ok,
@@ -12,6 +13,9 @@ SELECT
     countMerge(degraded) AS degraded
 FROM mv__http_status_15m__v0
 WHERE monitorId IN {{ Array(monitorIds, 'String', '1,666') }}
+    -- start at a local midnight so the oldest day is complete, not cut at the
+    -- 46-day TTL edge; stays inside the TTL for every zone (at most 45d + 14h)
+    AND time >= toStartOfDay(toTimeZone(now(), tz)) - INTERVAL 45 DAY
 GROUP BY day, monitorId
 ORDER BY day DESC
 
diff --git a/packages/tinybird/endpoints/endpoint__icmp_status_15m__v0.pipe b/packages/tinybird/endpoints/endpoint__icmp_status_15m__v0.pipe
index 91efe72cd..99d5eb70d 100644
--- a/packages/tinybird/endpoints/endpoint__icmp_status_15m__v0.pipe
+++ b/packages/tinybird/endpoints/endpoint__icmp_status_15m__v0.pipe
@@ -2,9 +2,10 @@ NODE endpoint
 SQL >
 
 %
+WITH {{ String(timezone, 'UTC') }} AS tz
 SELECT
     -- calendar date of the local day; the client re-keys it as UTC midnight like the 45d pipes
-    toDate(toTimeZone(time, {{ String(timezone, 'UTC') }})) AS day,
+    toDate(toTimeZone(time, tz)) AS day,
     monitorId,
     countMerge(count) AS count,
     countMerge(success) AS ok,
@@ -12,6 +13,9 @@ SELECT
     countMerge(degraded) AS degraded
 FROM mv__icmp_status_15m__v0
 WHERE monitorId IN {{ Array(monitorIds, 'String', '1,666') }}
+    -- start at a local midnight so the oldest day is complete, not cut at the
+    -- 46-day TTL edge; stays inside the TTL for every zone (at most 45d + 14h)
+    AND time >= toStartOfDay(toTimeZone(now(), tz)) - INTERVAL 45 DAY
 GROUP BY day, monitorId
 ORDER BY day DESC
 
diff --git a/packages/tinybird/endpoints/endpoint__tcp_status_15m__v0.pipe b/packages/tinybird/endpoints/endpoint__tcp_status_15m__v0.pipe
index 43275fe0f..ae4cbddbd 100644
--- a/packages/tinybird/endpoints/endpoint__tcp_status_15m__v0.pipe
+++ b/packages/tinybird/endpoints/endpoint__tcp_status_15m__v0.pipe
@@ -2,9 +2,10 @@ NODE endpoint
 SQL >
 
 %
+WITH {{ String(timezone, 'UTC') }} AS tz
 SELECT
     -- calendar date of the local day; the client re-keys it as UTC midnight like the 45d pipes
-    toDate(toTimeZone(time, {{ String(timezone, 'UTC') }})) AS day,
+    toDate(toTimeZone(time, tz)) AS day,
     monitorId,
     countMerge(count) AS count,
     countMerge(success) AS ok,
@@ -12,6 +13,9 @@ SELECT
     countMerge(degraded) AS degraded
 FROM mv__tcp_status_15m__v0
 WHERE monitorId IN {{ Array(monitorIds, 'String', '1,666') }}
+    -- start at a local midnight so the oldest day is complete, not cut at the
+    -- 46-day TTL edge; stays inside the TTL for every zone (at most 45d + 14h)
+    AND time >= toStartOfDay(toTimeZone(now(), tz)) - INTERVAL 45 DAY
 GROUP BY day, monitorId
 ORDER BY day DESC
 
diff --git a/packages/tinybird/src/client.test.ts b/packages/tinybird/src/client.test.ts
index 1bf010db5..cf40311ec 100644
--- a/packages/tinybird/src/client.test.ts
+++ b/packages/tinybird/src/client.test.ts
@@ -3,6 +3,7 @@ import { describe, test } from "@std/testing/bdd";
 import { z } from "zod";
 
 import {
+  isValidTimeZone,
   noopFlagSchema,
   OSTinybird,
   status15mParameters,
@@ -191,6 +192,17 @@ describe("status15mParameters", () => {
       ).toBe(timezone);
     }
   });
+
+  test("rejects zone names ClickHouse would 400 on, before the request", () => {
+    for (const timezone of ["Mars/Olympus", "", "GMT+1"]) {
+      const result = status15mParameters.safeParse({
+        monitorIds: ["1"],
+        timezone,
+      });
+      expect(result.success).toBe(false);
+    }
+    expect(isValidTimeZone("Etc/GMT+1")).toBe(true);
+  });
 });
 
 describe("status15mShape", () => {
diff --git a/packages/tinybird/src/client.ts b/packages/tinybird/src/client.ts
index 8443a1069..cbcbf18bd 100644
--- a/packages/tinybird/src/client.ts
+++ b/packages/tinybird/src/client.ts
@@ -14,17 +14,40 @@ const PUBLIC_CACHE = 300; // 5 * 60 = 300s = 5m
 const DEV_CACHE = 10 * 60; // 10m
 const REVALIDATE = env.NODE_ENV === "development" ? DEV_CACHE : 0;
 
+// Cheaper than a Tinybird 400 round trip for a zone ClickHouse won't know.
+const timeZoneValidity = new Map<string, boolean>();
+
+export function isValidTimeZone(timeZone: string): boolean {
+  let valid = timeZoneValidity.get(timeZone);
+  if (valid === undefined) {
+    try {
+      new Intl.DateTimeFormat("en-US", { timeZone });
+      valid = true;
+    } catch (error) {
+      if (!(error instanceof RangeError)) throw error;
+      valid = false;
+    }
+    timeZoneValidity.set(timeZone, valid);
+  }
+  return valid;
+}
+
 // 15-minute buckets regroup into local days for every IANA zone: all current
-// offsets are multiples of 15 minutes. ClickHouse rejects unknown zone names.
+// offsets are multiples of 15 minutes.
 export const status15mParameters = z.object({
   monitorIds: z.string().array(),
-  timezone: z.string().prefault("UTC"),
+  timezone: z
+    .string()
+    .refine(isValidTimeZone, "timezone must be an IANA zone name")
+    .prefault("UTC"),
 });
 
 /**
  * Same columns as the 45d pipes. `day` is the local calendar date re-keyed as
  * UTC midnight, the convention day-keyed consumers already read — a Berlin
  * 2026-10-14 stays "2026-10-14", not the 22:00Z instant of local midnight.
+ * `monitorId` is a String column in the http datasource and Int32 elsewhere,
+ * so the non-http getters pass `z.coerce.string()`.
  */
 export function status15mShape(monitorId: z.ZodType<string>) {
   return z.object({