diff --git a/shell/plugins/panels/clock/Model.js b/shell/plugins/panels/clock/Model.js
index 58d767f1..873db953 100644
--- a/shell/plugins/panels/clock/Model.js
+++ b/shell/plugins/panels/clock/Model.js
@@ -231,10 +231,17 @@ function lifeProgressPercent(age, expectancy) {
 // Always six rows of seven days. A fixed grid keeps the popup exactly the
 // same height in every month, so stepping through the year never makes the
 // panel jump under the pointer.
+//
+// Walked in UTC, where every day is 24 hours long. A local-midnight cursor has
+// to be resolved by the engine in zones that start DST at 00:00 -- Chile every
+// September, Cuba every March -- and V4 resolves the missing midnight backward
+// onto the previous day while V8 resolves it forward, so the local walk repeats
+// a date in the shell and not under the tests. A grid of civil dates never
+// needed a wall clock in the first place.
 function monthGrid(year, month, weekStart, todayKey) {
   var start = normalizedWeekStart(weekStart, 1)
-  var leading = (new Date(year, month, 1).getDay() - start + 7) % 7
-  var cursor = new Date(year, month, 1 - leading)
+  var leading = (new Date(Date.UTC(year, month, 1)).getUTCDay() - start + 7) % 7
+  var cursor = new Date(Date.UTC(year, month, 1 - leading))
   var today = String(todayKey || "")
   var weeks = []
 
@@ -242,10 +249,10 @@ function monthGrid(year, month, weekStart, todayKey) {
     var days = []
     var thursday = null
     for (var d = 0; d < 7; d++) {
-      var cellYear = cursor.getFullYear()
-      var cellMonth = cursor.getMonth()
-      var cellDay = cursor.getDate()
-      var weekday = cursor.getDay()
+      var cellYear = cursor.getUTCFullYear()
+      var cellMonth = cursor.getUTCMonth()
+      var cellDay = cursor.getUTCDate()
+      var weekday = cursor.getUTCDay()
       var key = dateKey(cellYear, cellMonth, cellDay)
       if (weekday === 4) thursday = { year: cellYear, month: cellMonth, day: cellDay }
       days.push({
@@ -258,7 +265,7 @@ function monthGrid(year, month, weekStart, todayKey) {
         weekend: weekday === 0 || weekday === 6,
         today: key === today
       })
-      cursor.setDate(cursor.getDate() + 1)
+      cursor.setUTCDate(cursor.getUTCDate() + 1)
     }
     // Number every row by the ISO week owning its Thursday. That is the
     // definition itself for Monday-start weeks, and the only answer that
@@ -273,9 +280,11 @@ function monthGrid(year, month, weekStart, todayKey) {
   return weeks
 }
 
+// UTC for the same reason as the grid: the month is read back off the date, so
+// a first of the month that has no local midnight would step into the wrong one.
 function stepMonth(year, month, delta) {
-  var target = new Date(year, Number(month) + Number(delta), 1)
-  return { year: target.getFullYear(), month: target.getMonth() }
+  var target = new Date(Date.UTC(year, Number(month) + Number(delta), 1))
+  return { year: target.getUTCFullYear(), month: target.getUTCMonth() }
 }
 
 if (typeof module !== "undefined") {
diff --git a/shell/plugins/panels/clock/Panel.qml b/shell/plugins/panels/clock/Panel.qml
index 4f4414bb..042c2ef8 100644
--- a/shell/plugins/panels/clock/Panel.qml
+++ b/shell/plugins/panels/clock/Panel.qml
@@ -41,7 +41,9 @@ Panel {
   property int viewYear: today.getFullYear()
   property int viewMonth: today.getMonth()
 
-  readonly property date viewDate: new Date(viewYear, viewMonth, 1)
+  // Local noon, so a first of the month with no midnight (Havana, April 2012)
+  // still names its own month; UTC would name the previous one west of Greenwich.
+  readonly property date viewDate: new Date(viewYear, viewMonth, 1, 12)
   readonly property bool viewingCurrentMonth: viewYear === today.getFullYear() && viewMonth === today.getMonth()
 
   // Pinned to today, not to the month being browsed — stepping through the
diff --git a/test/shell.d/clock-test.sh b/test/shell.d/clock-test.sh
index d2bde8a1..5b11f112 100755
--- a/test/shell.d/clock-test.sh
+++ b/test/shell.d/clock-test.sh
@@ -110,6 +110,57 @@ assertDeepEqual(julySunday.map(week => week.week), [27, 28, 29, 30, 31, 32], 'ca
 const januarySunday = calendar.monthGrid(2021, 0, 0, '')
 assertEqual(januarySunday[0].week, 53, 'calendar carries the previous ISO year into a straddling first row')
 
+// Zones that start DST at 00:00 have a calendar day with no local midnight, and
+// the engines disagree about which side of the gap it falls on: V4 resolves it
+// backward onto the previous date, V8 forward. Node therefore cannot see the
+// duplicated day the shell draws, so pin the property that makes the question
+// moot -- the grid is walked in UTC and never asks for a wall clock.
+const RealDate = Date
+class LocalTimeIsForbidden extends RealDate {
+  constructor(...args) {
+    if (args.length > 1) throw new Error('built a Date from local components')
+    super(...args)
+  }
+  getFullYear() { throw new Error('read the local year') }
+  getMonth() { throw new Error('read the local month') }
+  getDate() { throw new Error('read the local day') }
+  getDay() { throw new Error('read the local weekday') }
+  setDate() { throw new Error('stepped the local day') }
+}
+
+function withoutLocalTime(build) {
+  global.Date = LocalTimeIsForbidden
+  try {
+    return { value: build(), localTimeUse: '' }
+  } catch (error) {
+    return { value: null, localTimeUse: error.message }
+  } finally {
+    global.Date = RealDate
+  }
+}
+
+const september = withoutLocalTime(() => calendar.monthGrid(2026, 8, 0, ''))
+assertEqual(september.localTimeUse, '', 'calendar builds the month grid without reading local time')
+assertDeepEqual(
+  september.value.slice(0, 2).flatMap(week => week.days).map(day => day.day),
+  [30, 31, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
+  'calendar runs September 2026 straight through the Chilean DST midnight'
+)
+
+const stepped = withoutLocalTime(() => calendar.stepMonth(2026, 8, 1))
+assertEqual(stepped.localTimeUse, '', 'calendar steps months without reading local time')
+assertDeepEqual(stepped.value, { year: 2026, month: 9 }, 'calendar steps from September to October')
+
+// Samoa skipped 30 December 2011 outright, a gap even V8 cannot paper over.
+const previousTZ = process.env.TZ
+process.env.TZ = 'Pacific/Apia'
+const apia = calendar.monthGrid(2011, 11, 1, '')
+if (previousTZ === undefined) delete process.env.TZ
+else process.env.TZ = previousTZ
+assertDeepEqual(apia[4].days.map(day => day.day), [26, 27, 28, 29, 30, 31, 1], 'calendar keeps a day the local zone skipped')
+
+assert(/viewDate: new Date\(viewYear, viewMonth, 1, 12\)/.test(panelSource), 'calendar names the heading month from a noon that always exists')
+
 // ---- stepping
 assertDeepEqual(calendar.stepMonth(2026, 0, 1), { year: 2026, month: 1 }, 'calendar steps to the next month')
 assertDeepEqual(calendar.stepMonth(2026, 0, -1), { year: 2025, month: 11 }, 'calendar steps back across the new year')