diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8422b2aa1..0b12d2369 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Not released
 
+- Fix time zone handling in week counts, separate getMonday and getUTCMonday utilities [#879](https://github.com/CartoDB/carto-react/pull/879)
+
 ## 3.0.0
 
 ### 3.0.0-alpha.12 (2024-06-14)
diff --git a/packages/react-core/__tests__/utils/dateUtils.test.js b/packages/react-core/__tests__/utils/dateUtils.test.js
new file mode 100644
index 000000000..43c59b480
--- /dev/null
+++ b/packages/react-core/__tests__/utils/dateUtils.test.js
@@ -0,0 +1,66 @@
+import { getMonday, getUTCMonday } from '../../src/utils/dateUtils';
+
+const TEST_CASES = [
+  {
+    title: 'monday',
+    date: [2023, 9, 4],
+    expected: [2023, 9, 4]
+  },
+  {
+    title: 'monday, cross year',
+    date: [2014, 12, 1],
+    expected: [2014, 12, 1]
+  },
+  {
+    title: 'monday, february/march normal year',
+    date: [2015, 2, 23],
+    expected: [2015, 2, 23]
+  },
+  {
+    title: 'monday, february/march step year',
+    date: [2016, 2, 22],
+    expected: [2016, 2, 22]
+  },
+  {
+    title: 'sunday, cross year',
+    date: [2023, 1, 1],
+    expected: [2022, 12, 26]
+  },
+  {
+    title: 'saturday, february/march step year',
+    date: [2024, 3, 2],
+    expected: [2024, 2, 26]
+  }
+];
+
+/** Returns midnight (local time) for given year/month/date. */
+function createDate([year, month, date]) {
+  return new Date(year, month - 1, date);
+}
+
+/** Returns midnight (UTC) for given year/month/date. */
+function createUTCDate([year, month, date]) {
+  return new Date(Date.UTC(year, month - 1, date));
+}
+
+describe('getMonday', () => {
+  for (const { date, expected, title } of TEST_CASES) {
+    const expectedString = createDate(expected).toLocaleString();
+    it(`${date} ===> ${expectedString} - ${title}`, () => {
+      const local = getMonday(createDate(date));
+      const localString = new Date(local).toLocaleString();
+      expect(localString).toBe(expectedString);
+    });
+  }
+});
+
+describe('getUTCMonday', () => {
+  for (const { date, expected, title } of TEST_CASES) {
+    const expectedString = createUTCDate(expected).toISOString();
+    it(`${date} ===> ${expectedString} - ${title}`, () => {
+      const utc = getUTCMonday(createUTCDate(date));
+      const utcString = new Date(utc).toISOString();
+      expect(utcString).toBe(expectedString);
+    });
+  }
+});
diff --git a/packages/react-core/src/index.d.ts b/packages/react-core/src/index.d.ts
index be394717d..7b1ea9085 100644
--- a/packages/react-core/src/index.d.ts
+++ b/packages/react-core/src/index.d.ts
@@ -7,7 +7,7 @@ export {
   REQUEST_GET_MAX_URL_LENGTH
 } from './utils/requestsUtils';
 
-export { getMonday } from './utils/dateUtils';
+export { getMonday, getUTCMonday } from './utils/dateUtils';
 
 export { InvalidColumnError } from './utils/InvalidColumnError';
 
diff --git a/packages/react-core/src/index.js b/packages/react-core/src/index.js
index 2e31d74bb..754c5acbb 100644
--- a/packages/react-core/src/index.js
+++ b/packages/react-core/src/index.js
@@ -5,7 +5,7 @@ export {
   REQUEST_GET_MAX_URL_LENGTH
 } from './utils/requestsUtils';
 
-export { getMonday } from './utils/dateUtils';
+export { getMonday, getUTCMonday } from './utils/dateUtils';
 
 export { InvalidColumnError } from './utils/InvalidColumnError';
 
diff --git a/packages/react-core/src/operations/groupByDate.js b/packages/react-core/src/operations/groupByDate.js
index fdeee46df..25e17eaac 100644
--- a/packages/react-core/src/operations/groupByDate.js
+++ b/packages/react-core/src/operations/groupByDate.js
@@ -1,4 +1,4 @@
-import { getMonday } from '../utils/dateUtils';
+import { getUTCMonday } from '../utils/dateUtils';
 import { aggregate, aggregationFunctions } from './aggregation';
 import { GroupDateTypes } from './constants/GroupDateTypes';
 
@@ -6,7 +6,7 @@ const GROUP_KEY_FN_MAPPING = {
   // @ts-ignore
   [GroupDateTypes.YEARS]: (date) => Date.UTC(date.getUTCFullYear()),
   [GroupDateTypes.MONTHS]: (date) => Date.UTC(date.getUTCFullYear(), date.getUTCMonth()),
-  [GroupDateTypes.WEEKS]: (date) => getMonday(date),
+  [GroupDateTypes.WEEKS]: (date) => getUTCMonday(date),
   [GroupDateTypes.DAYS]: (date) =>
     Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate()),
   [GroupDateTypes.HOURS]: (date) =>
diff --git a/packages/react-core/src/utils/dateUtils.js b/packages/react-core/src/utils/dateUtils.js
index a415f919e..100118791 100644
--- a/packages/react-core/src/utils/dateUtils.js
+++ b/packages/react-core/src/utils/dateUtils.js
@@ -1,7 +1,24 @@
+/**
+ * Returns midnight (local time) on the Monday preceeding a given date, in
+ * milliseconds since the UNIX epoch.
+ */
 export function getMonday(date) {
   const dateCp = new Date(date);
   const day = dateCp.getDay();
   const diff = dateCp.getDate() - day + (day ? 1 : -6); // adjust when day is sunday
   dateCp.setDate(diff);
+  dateCp.setHours(0, 0, 0, 0);
+  return dateCp.getTime();
+}
+
+/**
+ * Returns midnight (UTC) on the Monday preceeding a given date, in
+ * milliseconds since the UNIX epoch.
+ */
+export function getUTCMonday(date) {
+  const dateCp = new Date(date);
+  const day = dateCp.getUTCDay();
+  const diff = dateCp.getUTCDate() - day + (day ? 1 : -6); // adjust when day is sunday
+  dateCp.setUTCDate(diff);
   return Date.UTC(dateCp.getUTCFullYear(), dateCp.getUTCMonth(), dateCp.getUTCDate());
 }
diff --git a/packages/react-ui/__tests__/widgets/utils/timeFormat.test.js b/packages/react-ui/__tests__/widgets/utils/timeFormat.test.js
index 8390e3e6f..62fde0eea 100644
--- a/packages/react-ui/__tests__/widgets/utils/timeFormat.test.js
+++ b/packages/react-ui/__tests__/widgets/utils/timeFormat.test.js
@@ -4,12 +4,19 @@ import { formatBucketRange } from '../../../src/widgets/TimeSeriesWidgetUI/utils
 describe('timeFormat', () => {
   describe('formatBucketRange', () => {
     describe('buckets from date', () => {
+      /** https://stackoverflow.com/a/33909265 */
+      function parseISOLocal(s) {
+        var b = s.split(/\D/);
+        return new Date(b[0], b[1] - 1, b[2], b[3] ?? 0, b[4] ?? 0, b[5] ?? 0);
+      }
       function defineCases(cases) {
         cases.forEach(({ date, expected, title, ...params }) =>
           it(`${date} / ${params.stepMultiplier ?? 1} ${
             params.stepSize
           } ===> ${expected} ${title ? `- ${title}` : ''}`, () =>
-            expect(formatBucketRange({ date: new Date(date), ...params })).toBe(expected))
+            expect(formatBucketRange({ date: parseISOLocal(date), ...params })).toBe(
+              expected
+            ))
         );
       }
       describe('second', () => {