diff --git a/goldens/public-api/common/common.d.ts b/goldens/public-api/common/common.d.ts
index 5481b3eae4bfe..d7f8438c85aa0 100644
--- a/goldens/public-api/common/common.d.ts
+++ b/goldens/public-api/common/common.d.ts
@@ -61,13 +61,13 @@ export declare function getLocaleDateFormat(locale: string, width: FormatWidth):
 
 export declare function getLocaleDateTimeFormat(locale: string, width: FormatWidth): string;
 
-export declare function getLocaleDayNames(locale: string, formStyle: FormStyle, width: TranslationWidth): string[];
+export declare function getLocaleDayNames(locale: string, formStyle: FormStyle, width: TranslationWidth): ReadonlyArray<string>;
 
-export declare function getLocaleDayPeriods(locale: string, formStyle: FormStyle, width: TranslationWidth): [string, string];
+export declare function getLocaleDayPeriods(locale: string, formStyle: FormStyle, width: TranslationWidth): Readonly<[string, string]>;
 
 export declare function getLocaleDirection(locale: string): 'ltr' | 'rtl';
 
-export declare function getLocaleEraNames(locale: string, width: TranslationWidth): [string, string];
+export declare function getLocaleEraNames(locale: string, width: TranslationWidth): Readonly<[string, string]>;
 
 export declare function getLocaleExtraDayPeriodRules(locale: string): (Time | [Time, Time])[];
 
@@ -77,7 +77,7 @@ export declare function getLocaleFirstDayOfWeek(locale: string): WeekDay;
 
 export declare function getLocaleId(locale: string): string;
 
-export declare function getLocaleMonthNames(locale: string, formStyle: FormStyle, width: TranslationWidth): string[];
+export declare function getLocaleMonthNames(locale: string, formStyle: FormStyle, width: TranslationWidth): ReadonlyArray<string>;
 
 export declare function getLocaleNumberFormat(locale: string, type: NumberFormatStyle): string;
 
diff --git a/packages/common/src/i18n/locale_data_api.ts b/packages/common/src/i18n/locale_data_api.ts
index a4661fde9349c..20221f759bab2 100644
--- a/packages/common/src/i18n/locale_data_api.ts
+++ b/packages/common/src/i18n/locale_data_api.ts
@@ -233,7 +233,7 @@ export function getLocaleId(locale: string): string {
  * @publicApi
  */
 export function getLocaleDayPeriods(
-    locale: string, formStyle: FormStyle, width: TranslationWidth): [string, string] {
+    locale: string, formStyle: FormStyle, width: TranslationWidth): Readonly<[string, string]> {
   const data = ɵfindLocaleData(locale);
   const amPmData = <[string, string][][]>[
     data[ɵLocaleDataIndex.DayPeriodsFormat], data[ɵLocaleDataIndex.DayPeriodsStandalone]
@@ -255,7 +255,7 @@ export function getLocaleDayPeriods(
  * @publicApi
  */
 export function getLocaleDayNames(
-    locale: string, formStyle: FormStyle, width: TranslationWidth): string[] {
+    locale: string, formStyle: FormStyle, width: TranslationWidth): ReadonlyArray<string> {
   const data = ɵfindLocaleData(locale);
   const daysData =
       <string[][][]>[data[ɵLocaleDataIndex.DaysFormat], data[ɵLocaleDataIndex.DaysStandalone]];
@@ -276,7 +276,7 @@ export function getLocaleDayNames(
  * @publicApi
  */
 export function getLocaleMonthNames(
-    locale: string, formStyle: FormStyle, width: TranslationWidth): string[] {
+    locale: string, formStyle: FormStyle, width: TranslationWidth): ReadonlyArray<string> {
   const data = ɵfindLocaleData(locale);
   const monthsData =
       <string[][][]>[data[ɵLocaleDataIndex.MonthsFormat], data[ɵLocaleDataIndex.MonthsStandalone]];
@@ -287,7 +287,6 @@ export function getLocaleMonthNames(
 /**
  * Retrieves Gregorian-calendar eras for the given locale.
  * @param locale A locale code for the locale format rules to use.
- * @param formStyle The required grammatical form.
  * @param width The required character width.
 
  * @returns An array of localized era strings.
@@ -296,7 +295,8 @@ export function getLocaleMonthNames(
  *
  * @publicApi
  */
-export function getLocaleEraNames(locale: string, width: TranslationWidth): [string, string] {
+export function getLocaleEraNames(
+    locale: string, width: TranslationWidth): Readonly<[string, string]> {
   const data = ɵfindLocaleData(locale);
   const erasData = <[string, string][]>data[ɵLocaleDataIndex.Eras];
   return getLastDefinedValue(erasData, width);
diff --git a/packages/common/test/i18n/locale_data_api_spec.ts b/packages/common/test/i18n/locale_data_api_spec.ts
index be6be2501971d..406e1327dbcb5 100644
--- a/packages/common/test/i18n/locale_data_api_spec.ts
+++ b/packages/common/test/i18n/locale_data_api_spec.ts
@@ -13,7 +13,7 @@ import localeHe from '@angular/common/locales/he';
 import localeZh from '@angular/common/locales/zh';
 import {ɵregisterLocaleData, ɵunregisterLocaleData} from '@angular/core';
 
-import {FormatWidth, getCurrencySymbol, getLocaleDateFormat, getLocaleDirection, getNumberOfCurrencyDigits} from '../../src/i18n/locale_data_api';
+import {FormatWidth, FormStyle, getCurrencySymbol, getLocaleDateFormat, getLocaleDayNames, getLocaleDirection, getLocaleMonthNames, getNumberOfCurrencyDigits, TranslationWidth} from '../../src/i18n/locale_data_api';
 
 {
   describe('locale data api', () => {
@@ -71,5 +71,96 @@ import {FormatWidth, getCurrencySymbol, getLocaleDateFormat, getLocaleDirection,
         expect(getLocaleDirection('en')).toEqual('ltr');
       });
     });
+
+    describe('getLocaleDayNames', () => {
+      it('should return english short list of days', () => {
+        expect(
+            getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Short),
+            )
+            .toEqual(['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa']);
+      });
+
+      it('should return french short list of days', () => {
+        expect(
+            getLocaleDayNames('fr-CA', FormStyle.Format, TranslationWidth.Short),
+            )
+            .toEqual(['di', 'lu', 'ma', 'me', 'je', 've', 'sa']);
+      });
+
+      it('should return english wide list of days', () => {
+        expect(
+            getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Wide),
+            )
+            .toEqual(
+                ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']);
+      });
+
+      it('should return french wide list of days', () => {
+        expect(
+            getLocaleDayNames('fr-CA', FormStyle.Format, TranslationWidth.Wide),
+            )
+            .toEqual(['dimanche', 'lundi', 'mardi', 'mercredi', 'jeudi', 'vendredi', 'samedi']);
+      });
+
+      it('should return the full short list of days after manipulations', () => {
+        const days =
+            Array.from(getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Short));
+
+        days.splice(2);
+        days.push('unexisting_day');
+
+        const newDays = getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Short);
+
+        expect(newDays.length).toBe(7);
+
+        expect(newDays).toEqual(['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa']);
+      });
+    });
+
+    describe('getLocaleMonthNames', () => {
+      it('should return english abbreviated list of month', () => {
+        expect(getLocaleMonthNames('en-US', FormStyle.Format, TranslationWidth.Abbreviated))
+            .toEqual([
+              'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
+            ]);
+      });
+
+      it('should return french abbreviated list of month', () => {
+        expect(getLocaleMonthNames('fr-CA', FormStyle.Format, TranslationWidth.Abbreviated))
+            .toEqual([
+              'janv.', 'févr.', 'mars', 'avr.', 'mai', 'juin', 'juil.', 'août', 'sept.', 'oct.',
+              'nov.', 'déc.'
+            ]);
+      });
+
+      it('should return english wide list of month', () => {
+        expect(getLocaleMonthNames('en-US', FormStyle.Format, TranslationWidth.Wide)).toEqual([
+          'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September',
+          'October', 'November', 'December'
+        ]);
+      });
+
+      it('should return french wide list of month', () => {
+        expect(getLocaleMonthNames('fr-CA', FormStyle.Format, TranslationWidth.Wide)).toEqual([
+          'janvier', 'février', 'mars', 'avril', 'mai', 'juin', 'juillet', 'août', 'septembre',
+          'octobre', 'novembre', 'décembre'
+        ]);
+      });
+
+      it('should return the full abbreviated list of month after manipulations', () => {
+        const month = Array.from(
+            getLocaleMonthNames('en-US', FormStyle.Format, TranslationWidth.Abbreviated));
+        month.splice(2);
+        month.push('unexisting_month');
+
+        const newMonth =
+            getLocaleMonthNames('en-US', FormStyle.Format, TranslationWidth.Abbreviated);
+
+        expect(newMonth.length).toBe(12);
+
+        expect(newMonth).toEqual(
+            ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']);
+      });
+    });
   });
 }