Javascript to get temperature, humidity, precipitation, wind, and solr radiation from Weather Underground "history" API

gistfile1.js

function get_weather_history(year, month, day, query, apikey) {  
  if(month < 10) {
    month = "0" + month;
  }
  if(day < 10) {
    day = "0" + day;
  }
  var ymd = year + "" + month + "" + day;
  var url = "http://api.wunderground.com/api/" + apikey + "/history_" + ymd + "/q/" + query + ".json";

  Logger.log("Calling URL: " + url);
  var response = UrlFetchApp.fetch(url);
  var json = response.getContentText();
  var data = JSON.parse(json);
  var avg_temp = data['history']['dailysummary'][0]['meantempi'];
  var precip_in = data['history']['dailysummary'][0]['precipi'];
  if(precip_in == "T") { // TODO what does this mean?
    precip_in = "0.00";
  }
  var max_temp = data['history']['dailysummary'][0]['maxtempi'];
  var min_temp = data['history']['dailysummary'][0]['mintempi'];
  var gdd = data['history']['dailysummary'][0]['gdegreedays'];
  var hdd = data['history']['dailysummary'][0]['heatingdegreedays'];
  var cdd = data['history']['dailysummary'][0]['coolingdegreedays'];
  var wind = data['history']['dailysummary'][0]['meanwindspdi'];
  
  var humidity = data['history']['dailysummary'][0]['humidity'];
  var min_humidity = data['history']['dailysummary'][0]['minhumidity'];
  var max_humidity = data['history']['dailysummary'][0]['maxhumidity'];

  // Calculate the solar radiation in Joules/m^2 given Watt/m^2
  var t0, t1;
  var sr0, sr1;
  var t0 = 0; // midnight
  var sr0 = 0; // no radiation at midnight
  var srtotal = 0.0;
  // Numerically integrate individual observations
  data['history']['observations'].forEach(function(observation) {
    // Convert times to seconds since 1 Joule = 1 Watt*second
    t1 = parseInt(observation['date']['hour'], 10)*60*60 + parseInt(observation['date']['min'], 10)*60; // seconds
    sr1 = parseFloat(observation['solarradiation']);
    srtotal += (t1-t0) * ((sr1 + sr0)/2.0); // Trapezoid rule (thanks, grad school!)
    t0 = t1;
    sr0 = sr1;
  });
  
  var sr_MJ = srtotal / 1000000.0; // Guess that physics degree paid off finally
  
  return [parseFloat(min_temp),
          parseFloat(avg_temp),
          parseFloat(max_temp),
          parseFloat(precip_in),
          sr_MJ,
          parseFloat(wind),
          parseFloat(min_humidity),
          parseFloat(humidity),
          parseFloat(max_humidity)];
}