From a223846e1336d12d31a1a01143f2a29fe67663e8 Mon Sep 17 00:00:00 2001
From: Severin Gehwolf <sgehwolf@redhat.com>
Date: Thu, 27 Aug 2026 11:38:12 +0200
Subject: [PATCH] Backport 8da9af4dc032d93a0b5f46644b4b9f2c3c9dc62f

---
 make/data/cldr/common/supplemental/metaZones.xml        | 4 +++-
 test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java | 7 ++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/make/data/cldr/common/supplemental/metaZones.xml b/make/data/cldr/common/supplemental/metaZones.xml
index ab8c0a133fc..aa096d5133a 100644
--- a/make/data/cldr/common/supplemental/metaZones.xml
+++ b/make/data/cldr/common/supplemental/metaZones.xml
@@ -57,6 +57,7 @@ For terms of use, see http://www.unicode.org/copyright.html
 				<usesMetazone to="1984-03-16 00:00" mzone="Europe_Western"/>
 				<usesMetazone to="1985-12-31 23:00" from="1984-03-16 00:00" mzone="Europe_Central"/>
 				<usesMetazone to="2018-10-28 02:00" from="1985-12-31 23:00" mzone="Europe_Western"/>
+				<usesMetazone from="2026-09-20 01:00" mzone="Europe_Western"/>
 			</timezone>
 			<timezone type="Africa/Ceuta">
 				<usesMetazone to="1984-03-16 00:00" mzone="Europe_Western"/>
@@ -80,6 +81,7 @@ For terms of use, see http://www.unicode.org/copyright.html
 			<timezone type="Africa/El_Aaiun">
 				<usesMetazone to="1976-04-14 01:00" mzone="Africa_FarWestern"/>
 				<usesMetazone to="2018-10-28 02:00" from="1976-04-14 01:00" mzone="Europe_Western"/>
+				<usesMetazone from="2026-09-20 01:00" mzone="Europe_Western"/>
 			</timezone>
 			<timezone type="Africa/Freetown">
 				<usesMetazone mzone="GMT"/>
@@ -382,7 +384,7 @@ For terms of use, see http://www.unicode.org/copyright.html
 				<usesMetazone mzone="Atlantic"/>
 			</timezone>
 			<timezone type="America/Edmonton">
-				<usesMetazone mzone="America_Mountain"/>
+				<usesMetazone mzone="America_Mountain" stdOffset="-07" dstOffset="-06"/>
 			</timezone>
 			<timezone type="America/Eirunepe">
 				<usesMetazone to="2008-06-24 05:00" mzone="Acre"/>
diff --git a/test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java b/test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java
index af565652637..dec4df6c78a 100644
--- a/test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java
+++ b/test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java
@@ -24,8 +24,7 @@
  /*
  * @test
  * @bug 8181157 8202537 8234347 8236548 8261279 8322647 8174269 8346948
- *      8381379 8382020 8384043 8390388
- *      8381379 8382020 8384043
+ *      8381379 8382020 8384043 8390388 8390380
  * @modules jdk.localedata
  * @summary Checks CLDR time zone names are generated correctly at
  * either build or runtime
@@ -277,7 +276,9 @@ private static Stream<Arguments> explicitDstOffsets() {
             Arguments.of(ZonedDateTime.of(2026, 4, 5, 0, 0, 0, 0, ZoneId.of("Eire")), "Irish Standard Time"),
             Arguments.of(ZonedDateTime.of(2026, 12, 5, 0, 0, 0, 0, ZoneId.of("Eire")), "Greenwich Mean Time"),
             Arguments.of(ZonedDateTime.of(2026, 4, 5, 0, 0, 0, 0, ZoneId.of("America/Vancouver")), "Pacific Daylight Time"),
-            Arguments.of(ZonedDateTime.of(2026, 12, 5, 0, 0, 0, 0, ZoneId.of("America/Vancouver")), "Pacific Daylight Time")
+            Arguments.of(ZonedDateTime.of(2026, 12, 5, 0, 0, 0, 0, ZoneId.of("America/Vancouver")), "Pacific Daylight Time"),
+            Arguments.of(ZonedDateTime.of(2026, 1, 5, 0, 0, 0, 0, ZoneId.of("America/Edmonton")), "Mountain Standard Time"),
+            Arguments.of(ZonedDateTime.of(2026, 7, 5, 0, 0, 0, 0, ZoneId.of("America/Edmonton")), "Mountain Daylight Time")
         );
     }