diff --git a/packages/@internationalized/date/src/queries.ts b/packages/@internationalized/date/src/queries.ts
index 732594d729d..ce48d95d75c 100644
--- a/packages/@internationalized/date/src/queries.ts
+++ b/packages/@internationalized/date/src/queries.ts
@@ -268,7 +268,9 @@ function getWeekStart(locale: string): number {
     }
     let region = getRegion(locale);
     if (locale.includes('-fw-')) {
-      let day = locale.split('-fw-')[1];
+      // pull the value for the attribute fw from strings such as en-US-u-ca-iso8601-fw-tue or en-US-u-ca-iso8601-fw-mon-nu-thai
+      // where the fw attribute could be followed by another unicode locale extension or not
+      let day = locale.split('-fw-')[1].split('-')[0];
       if (day === 'mon') {
         weekInfo = {firstDay: 1};
       } else if (day === 'tue') {
@@ -284,7 +286,7 @@ function getWeekStart(locale: string): number {
       } else {
         weekInfo = {firstDay: 0};
       }
-    } else if (locale.includes('u-ca-iso8601')) {
+    } else if (locale.includes('-ca-iso8601')) {
       weekInfo = {firstDay: 1};
     } else {
       weekInfo = {firstDay: region ? weekStartData[region] || 0 : 0};
diff --git a/packages/@internationalized/date/tests/queries.test.js b/packages/@internationalized/date/tests/queries.test.js
index 8ae3f8c3a54..40fceb3494e 100644
--- a/packages/@internationalized/date/tests/queries.test.js
+++ b/packages/@internationalized/date/tests/queries.test.js
@@ -281,6 +281,11 @@ describe('queries', function () {
 
       // override first day of week
       expect(startOfWeek(new CalendarDate(2021, 8, 4), 'en-US-u-ca-iso8601-fw-tue')).toEqual(new CalendarDate(2021, 8, 3));
+
+      // override applied if extension appears in the middle of other extensions
+      expect(startOfWeek(new CalendarDate(2021, 8, 4), 'en-US-u-nu-thai-ca-iso8601')).toEqual(new CalendarDate(2021, 8, 2));
+      expect(startOfWeek(new CalendarDate(2021, 8, 4), 'en-US-u-nu-thai-ca-iso8601-fw-tue')).toEqual(new CalendarDate(2021, 8, 3));
+      expect(startOfWeek(new CalendarDate(2021, 8, 4), 'en-US-u-ca-iso8601-fw-tue-nu-thai')).toEqual(new CalendarDate(2021, 8, 3));
     });
   });
 
diff --git a/packages/react-aria-components/stories/Calendar.stories.tsx b/packages/react-aria-components/stories/Calendar.stories.tsx
index 0703be28137..4caa40f4229 100644
--- a/packages/react-aria-components/stories/Calendar.stories.tsx
+++ b/packages/react-aria-components/stories/Calendar.stories.tsx
@@ -161,7 +161,7 @@ export const CalendarFirstDayOfWeekExample: StoryObj<CalendarFirstDayOfWeekExamp
   argTypes: {
     locale: {
       control: 'select',
-      options: ['en-US-u-ca-iso8601-fw-tue', 'en-US-u-ca-iso8601', 'en-US', 'fr-FR-u-ca-iso8601-fw-tue', 'fr-FR-u-ca-iso8601', 'fr-FR']
+      options: ['en-US-u-ca-iso8601-fw-tue', 'en-US-u-ca-iso8601', 'en-US', 'fr-FR-u-ca-iso8601-fw-tue', 'fr-FR-u-ca-iso8601', 'fr-FR', 'en-US-u-ca-iso8601-fw-tue-nu-thai']
     }
   }
 };