diff --git a/modules/backend/formwidgets/DatePicker.php b/modules/backend/formwidgets/DatePicker.php
index 4718bf946..b10789b22 100644
--- a/modules/backend/formwidgets/DatePicker.php
+++ b/modules/backend/formwidgets/DatePicker.php
@@ -46,6 +46,12 @@ class DatePicker extends FormWidgetBase
      */
     public $yearRange = null;
 
+    /**
+     * @var int first day of the week
+     * eg: 0 (Sunday), 1 (Monday), 2 (Tuesday), etc.
+     */
+    public $firstDay = 0;
+
     //
     // Object properties
     //
@@ -66,6 +72,7 @@ class DatePicker extends FormWidgetBase
             'minDate',
             'maxDate',
             'yearRange',
+            'firstDay',
         ]);
 
         $this->mode = strtolower($this->mode);
@@ -112,6 +119,7 @@ class DatePicker extends FormWidgetBase
         $this->vars['minDate'] = $this->minDate;
         $this->vars['maxDate'] = $this->maxDate;
         $this->vars['yearRange'] = $this->yearRange;
+        $this->vars['firstDay'] = $this->firstDay;
         $this->vars['format'] = $this->format;
         $this->vars['formatMoment'] = $this->getDateFormatMoment();
         $this->vars['formatAlias'] = $this->getDateFormatAlias();
diff --git a/modules/backend/formwidgets/datepicker/partials/_datepicker.htm b/modules/backend/formwidgets/datepicker/partials/_datepicker.htm
index 53221db78..090c9a0b5 100644
--- a/modules/backend/formwidgets/datepicker/partials/_datepicker.htm
+++ b/modules/backend/formwidgets/datepicker/partials/_datepicker.htm
@@ -14,6 +14,7 @@
         <?php if ($minDate): ?>data-min-date="<?= $minDate ?>"<?php endif ?>
         <?php if ($maxDate): ?>data-max-date="<?= $maxDate ?>"<?php endif ?>
         <?php if ($yearRange): ?>data-year-range="<?= $yearRange ?>"<?php endif ?>
+        <?php if ($firstDay): ?>data-first-day="<?= $firstDay ?>"<?php endif ?>
     >
 
         <?php if ($mode == 'date'): ?>
diff --git a/modules/system/assets/ui/js/datepicker.js b/modules/system/assets/ui/js/datepicker.js
index 179ea2f43..b83e6fd09 100644
--- a/modules/system/assets/ui/js/datepicker.js
+++ b/modules/system/assets/ui/js/datepicker.js
@@ -102,6 +102,7 @@
 
         var pikadayOptions = {
             yearRange: this.options.yearRange,
+            firstDay: this.options.firstDay,
             format: dateFormat,
             setDefaultDate: now,
             onOpen: function() {
@@ -305,7 +306,8 @@
         minDate: null,
         maxDate: null,
         format: null,
-        yearRange: 10
+        yearRange: 10,
+        firstDay: 0
     }
 
     // PLUGIN DEFINITION
diff --git a/modules/system/assets/ui/storm-min.js b/modules/system/assets/ui/storm-min.js
index 7d68f9c3c..257f21158 100644
--- a/modules/system/assets/ui/storm-min.js
+++ b/modules/system/assets/ui/storm-min.js
@@ -2877,7 +2877,7 @@ this.$el=null
 this.options=null
 BaseProto.dispose.call(this)}
 DatePicker.prototype.initDatePicker=function(){var self=this,dateFormat=this.getDateFormat(),now=moment().tz(this.timezone).format(dateFormat)
-var pikadayOptions={yearRange:this.options.yearRange,format:dateFormat,setDefaultDate:now,onOpen:function(){var $field=$(this._o.trigger)
+var pikadayOptions={yearRange:this.options.yearRange,firstDay:this.options.firstDay,format:dateFormat,setDefaultDate:now,onOpen:function(){var $field=$(this._o.trigger)
 $(this.el).css({left:'auto',right:$(window).width()-$field.offset().left-$field.outerWidth()})},onSelect:function(){self.onSelectDatePicker.call(self,this.getMoment())}}
 var lang=this.getLang('datepicker',false)
 if(lang){pikadayOptions.i18n=lang}
@@ -2926,7 +2926,7 @@ if(!this.appTimezone){this.appTimezone='UTC'}
 if(!this.timezone){this.timezone='UTC'}}
 DatePicker.prototype.getLang=function(name,defaultValue){if($.oc===undefined||$.oc.lang===undefined){return defaultValue}
 return $.oc.lang.get(name,defaultValue)}
-DatePicker.DEFAULTS={minDate:null,maxDate:null,format:null,yearRange:10}
+DatePicker.DEFAULTS={minDate:null,maxDate:null,format:null,yearRange:10,firstDay:0}
 var old=$.fn.datePicker
 $.fn.datePicker=function(option){var args=Array.prototype.slice.call(arguments,1),items,result
 items=this.each(function(){var $this=$(this)