Q:

How to change Highcharts xAxis label color individually? 

I have been able to change the color of my charts xAxis labels by using the following:
Highcharts.chart('container', {
  chart: {
    marginBottom: 80
  },
  xAxis: {
    categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
    labels: {
      style: {
        color: 'red'
      }
    }
  },
  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]
  }]
});

Although, the above changes all xAxis labels to be red. 
How can I change each labels color individually, so that "Jan" is red, "Feb" is blue, etc. 
Working example

A:

You can use Axis.labels.formatter and return your label in html tag with style attribute, which can define your color. 
const color = {
    Jan: 'red',
  Feb: 'green',
  Mar: 'blue'
}

const chart = Highcharts.chart('container', {
  chart: {
    marginBottom: 80
  },
  xAxis: {
    categories: ['Jan', 'Feb', 'Mar'],
    labels: {
      formatter () {
        return `<span style="color: ${color[this.value]}">${this.value}</span>`
      }
    }
  },

  series: [{
    data: [29.9, 71.5, 106.4]
  }]
})

console.log(chart.series[0].data)

Live example:
http://jsfiddle.net/508jej83/

