var url = 'http://api.wunderground.com/api/5b85b19f7e8c43f1/forecast10day/q/37201.json';
var forecast;
getJSON(url, function(data){
forecast = data.forecast;
});
function getJSON(url, cb) {
var xhr = new XMLHttpRequest();
xhr.open('GET', url);
xhr.onload = function () {
if (this.status >= 200 && this.status < 400) {
cb(JSON.parse(this.response));
}
};
xhr.send()
}
forecast.txt_forecast.forecastday[0]