Add wind chill.

lib/helpers/json.dart

@@ -2,19 +2,18 @@
 
 import '/var/config.dart';
 import 'package:flutter/material.dart';
+import 'dart:math';
 
 String formatOpenWeatherData(var data) {
   String location = pullOpenWeatherCity(data),
       temp = pullOpenWeatherTemp(data),
       conditions = pullOpenWeatherConditions(data),
       windSpeed = pullOpenWeatherWind(data),
-      humidity = pullOpenWeatherHumidity(data),
-      windChill = "",
-      heatIndex = "",
-      comfort = "";
+      humidity = pullOpenWeatherHumidity(data);
 
-  // Always ask for Imperial units in API request
-  final String tempUnits = 'F', windUnits = 'mph', humidityUnits = '%';
+  String windChill = getWindChill(temp, windSpeed), heatIndex = "";
+
+  String comfort = "";
 
   String text =
       "$location is $temp$tempUnits and $conditions"
@@ -70,3 +69,30 @@ String pullOpenWeatherHumidity(var data) {
   }
   return humidity;
 }
+
+double calcWindChill(double temp, double windSpeed) {
+  // ## Wind Chill ##
+  // # Wind speed as noted in: https://answers.yahoo.com/question/index?qid=20091020183148AAHm3kB&guccounter=1
+  // # More official source: https://www.weather.gov/media/epz/wxcalc/windChill.pdf
+  double windChill =
+      35.74 +
+      (0.6215 * temp) -
+      (35.75 * pow(windSpeed, 0.16)) +
+      (0.4275 * temp * pow(windSpeed, 0.16));
+  if (debug) {
+    debugPrint("DEBUG: windChill = '$windChill'");
+  }
+  return windChill;
+}
+
+String getWindChill(String temp, String windSpeed) {
+  double temperature = double.parse(temp);
+  double wind = double.parse(windSpeed);
+
+  if (temperature < 50 && wind > 5) {
+    double windChill = calcWindChill((temperature), (wind));
+    return "My guess is that's a wind chill of $windChill$tempUnits";
+  }
+
+  return "";
+}