asyncExample.js

var async = require('async');
var request = require('request');

async.map({
  dubai : "Dubai",
  dublin : "Dublin",
  paris : "Paris",
  rome : "Rome"  
}, function(city, callback){
  request({
    url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=' + city,
    json : true
  }, function(err, response, weatherBody){
    callback(null, weatherBody.main.temp);  
  });
}, function(err, weatherResult){
  console.log(weatherResult);
});

async.parallel({
    dubai: function(callback) {    
      request({
        url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Dubai',
        json : true
      }, function(err, response, weatherBody){
        callback(null, weatherBody.main.temp);  
      });
    },
    dublin: function(callback){
      request({
        url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Dublin',
        json : true
      }, function(err, response, weatherBody){
        callback(null, weatherBody.main.temp);  
      });
    },
    paris: function(callback){
      request({
        url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Paris',
        json : true
      }, function(err, response, weatherBody){
        callback(null, weatherBody.main.temp);  
      });
    },
    rome: function(callback){
      request({
        url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Rome',
        json : true
      }, function(err, response, weatherBody){
        callback(null, weatherBody.main.temp);  
      });
    },
}, function(err, results) {
  if (err){
    console.error('stuff went wrong: ' + err);
    return;
  }
  console.log(results);
});

async.waterfall([
  function(callback){
    request({
      url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Dublin',
      json : true
    }, function(err, response, weatherBody){
      callback(null, weatherBody.main.temp);  
    });
  },
  function(dublinWeather, callback){
    request({
      url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Dubai',
      json : true
    }, function(err, response, weatherBody){
      var dubaiWeather = weatherBody.main.temp;
      callback(null, dubaiWeather + dublinWeather);  
    });
  },
  function(dubaiAndDublinWeather, callback){
    request({
      url : 'http://api.openweathermap.org/data/2.5/weather?appid=035957dcae9879b8e7c72469f4811705&q=Rome',
      json : true
    }, function(err, response, weatherBody){
      var romeWeather = weatherBody.main.temp;
      callback(null, dubaiAndDublinWeather + romeWeather);  
    });
  }
], function(err, dubaiAndDublinAndRomeWeather){
  console.log(dubaiAndDublinAndRomeWeather);
});