Implement weather calculations in the service

Weather/Service/Extensions.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ChrisKaczor.HomeMonitor.Weather.Service
+{
+    public static class Extensions
+    {
+        public static bool IsBetween<T>(this T item, T start, T end) where T : IComparable
+        {
+            return item.CompareTo(start) >= 0 && item.CompareTo(end) <= 0;
+        }
+    }
+}