diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3c088fd4fe5..771e9ed1aeb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -37,9 +37,7 @@
 ### Mixin
 
 * [CHANGE] Alerts: Removed obsolete `MimirQueriesIncorrect` alert that used test-exporter metrics. Test-exporter support was however removed in Mimir 2.0 release. #7774
-* [CHANGE] Fine-tuned `terminationGracePeriodSeconds` for the following components: #7364
-  * Querier: changed from `30` to `180`
-  * Query-scheduler: changed from `30` to `180`
+* [CHANGE] Alerts: Change threshold for `MimirBucketIndexNotUpdated` alert to fire before queries begin to fail due to bucket index age. #7879
 * [FEATURE] Dashboards: added 'Remote ruler reads networking' dashboard. #7751
 * [ENHANCEMENT] Alerts: allow configuring alerts range interval via `_config.base_alerts_range_interval_minutes`. #7591
 * [ENHANCEMENT] Dashboards: Add panels for monitoring distributor and ingester when using ingest-storage. These panels are disabled by default, but can be enabled using `show_ingest_storage_panels: true` config option. Similarly existing panels used when distributors and ingesters use gRPC for forwarding requests can be disabled by setting `show_grpc_ingestion_panels: false`. #7670 #7699
@@ -61,6 +59,9 @@
 ### Jsonnet
 
 * [CHANGE] Memcached: Change default read timeout for chunks and index caches to `750ms` from `450ms`. #7778
+* [CHANGE] Fine-tuned `terminationGracePeriodSeconds` for the following components: #7364
+  * Querier: changed from `30` to `180`
+  * Query-scheduler: changed from `30` to `180`
 * [ENHANCEMENT] Compactor: add `$._config.cortex_compactor_concurrent_rollout_enabled` option (disabled by default) that makes use of rollout-operator to speed up the rollout of compactors. #7783 #7878
 * [ENHANCEMENT] Shuffle-sharding: add `$._config.shuffle_sharding.ingest_storage_partitions_enabled` and `$._config.shuffle_sharding.ingester_partitions_shard_size` options, that allow configuring partitions shard size in ingest-storage mode. #7804
 * [BUGFIX] Guard against missing samples in KEDA queries. #7691
diff --git a/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml b/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
index 941ecb1ce29..95e65aea3cb 100644
--- a/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
+++ b/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
@@ -801,7 +801,7 @@ spec:
           }}.
         runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#mimirbucketindexnotupdated
       expr: |
-        min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 7200
+        min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 2100
       labels:
         severity: critical
   - name: mimir_compactor_alerts
diff --git a/operations/mimir-mixin-compiled-baremetal/alerts.yaml b/operations/mimir-mixin-compiled-baremetal/alerts.yaml
index 0efa8546bbb..cd503f25a29 100644
--- a/operations/mimir-mixin-compiled-baremetal/alerts.yaml
+++ b/operations/mimir-mixin-compiled-baremetal/alerts.yaml
@@ -775,7 +775,7 @@ groups:
         }}.
       runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#mimirbucketindexnotupdated
     expr: |
-      min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 7200
+      min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 2100
     labels:
       severity: critical
 - name: mimir_compactor_alerts
diff --git a/operations/mimir-mixin-compiled/alerts.yaml b/operations/mimir-mixin-compiled/alerts.yaml
index ef05886356b..46541a667ff 100644
--- a/operations/mimir-mixin-compiled/alerts.yaml
+++ b/operations/mimir-mixin-compiled/alerts.yaml
@@ -789,7 +789,7 @@ groups:
         }}.
       runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#mimirbucketindexnotupdated
     expr: |
-      min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 7200
+      min by(cluster, namespace, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 2100
     labels:
       severity: critical
 - name: mimir_compactor_alerts
diff --git a/operations/mimir-mixin/alerts/blocks.libsonnet b/operations/mimir-mixin/alerts/blocks.libsonnet
index 28c3073e140..eeec268f026 100644
--- a/operations/mimir-mixin/alerts/blocks.libsonnet
+++ b/operations/mimir-mixin/alerts/blocks.libsonnet
@@ -220,10 +220,13 @@
           },
         },
         {
-          // Alert if the bucket index has not been updated for a given user.
+          // Alert if the bucket index has not been updated for a given user. The default update interval is 900 seconds
+          // so we alert if we've missed two updates plus a 300 second buffer to avoid false-positives. It's important
+          // that this alert fire before queriers start to return errors because the bucket index is too old (3600 seconds
+          // by default).
           alert: $.alertName('BucketIndexNotUpdated'),
           expr: |||
-            min by(%(alert_aggregation_labels)s, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 7200
+            min by(%(alert_aggregation_labels)s, user) (time() - cortex_bucket_index_last_successful_update_timestamp_seconds) > 2100
           ||| % $._config,
           labels: {
             severity: 'critical',