diff --git a/sohstationviewer/view/ui/calendar_widget.py b/sohstationviewer/view/ui/calendar_widget.py
new file mode 100644
index 0000000000000000000000000000000000000000..bb9e265d544beac1fd9a4201e5fcb6abb99f6443
--- /dev/null
+++ b/sohstationviewer/view/ui/calendar_widget.py
@@ -0,0 +1,56 @@
+from PySide2 import QtCore, QtGui, QtWidgets
+
+
+class CalendarWidget(QtWidgets.QCalendarWidget):
+
+    def __init__(self, parent):
+
+        super().__init__(parent)
+        self.setupUi()
+        self._showDayOfYear = getattr(self, 'toggleDayOfYear', None) == None
+
+
+    def setupUi(self):
+        self.setMinimumWidth(300)
+        self.setMinimumHeight(275)
+
+        navbar = self.findChild(QtWidgets.QWidget, 'qt_calendar_navigationbar')
+
+        if navbar:
+            # self.toggleDayOfYear = QtWidgets.QPushButton('Show DOY', navbar)
+            # self.toggleDayOfYear = QtWidgets.QCheckBox('Show DOY', navbar)
+            self.toggleDayOfYear = QtWidgets.QCheckBox('Show DOY')
+            # navbar.layout().addWidget(self.toggleDayOfYear)
+            navbar.layout().insertWidget(1, self.toggleDayOfYear)
+
+            self.toggleDayOfYear.toggled.connect(self.setShowDayOfYear)
+            self.toggleDayOfYear.setCheckable(True)
+
+            palette = self.toggleDayOfYear.palette()
+            palette.setColor(QtGui.QPalette.WindowText, QtGui.QColor('white'))
+            self.toggleDayOfYear.setPalette(palette)
+
+            self.toggleDayOfYear.show()
+
+
+    def showDayOfYear(self):
+        return self._showDayOfYear
+
+    @QtCore.Slot(bool)
+    def setShowDayOfYear(self, value):
+        self._showDayOfYear = value
+        self.updateCells()
+
+    def paintCell(self, painter, rect, date):
+        super().paintCell(painter, rect, date)
+
+        painter.save()
+
+        if self.showDayOfYear():
+            color = QtGui.QColor('red')
+            font = painter.font()
+            font.setPointSize(font.pointSize() * 0.9)
+            painter.setFont(font)
+            painter.setPen(color)
+            painter.drawText(rect.bottomLeft(), str(date.dayOfYear()))
+        painter.restore()