Highcharts dynamically change bar color based on value

Solution:

You can use color zones (API) to have different colors based on the value of a column.

An example with values below/above the value 10 having different colors (JSFiddle):

plotOptions: {
    column: {
        zones: [{
            value: 10, // Values up to 10 (not including) ...
            color: 'blue' // ... have the color blue.
        },{
            color: 'red' // Values from 10 (including) and up have the color red
        }]
    }
}

In the parser you can replace that:

$.each(response, function(i, item) {
        categorySeries .push(response[i].dateVal);                  
        dataSeries.push(response[i].count);             
    });

with

$.each(response, function(i, item) {
    categorySeries.push(response[i].dateVal);
    if(response[i].count >= 10) {
        dataSeries.push({
        y: response[i].count,
        color: 'red'
      });
    }
    else {
        dataSeries.push(response[i].count);
    }
});

or use zones.