ElementStacks

HTML

<script src="http://code.highcharts.com/2.2.4/highcharts.js"></script>
<div id="container" style="height: 400px; width: 500px"></div>

JavaScript

var chart = new Highcharts.Chart({
    chart: {
        renderTo: 'container'
    },
    xAxis: {        
        type: 'datetime',
        labels: {
            formatter: function() {
                var monthStr = Highcharts.dateFormat('%B', this.value);
                var firstLetter = parseInt(monthStr) / 3
                console.log(monthStr);
                return firstLetter;
            }
        },
        tickInterval: 30 * 24 * 3600 * 1000
    },
    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
        pointStart: Date.UTC(2010, 0, 1),
        pointInterval: 30 * 24 * 3600 * 1000 // one day
    }]
});