Added charset utf-8 to all files.

sass/partials/_functions.scss

@@ -1,3 +1,4 @@
+@charset "utf-8";
 // Functions for fixing unicode characters see link below if any questions
 // https://github.com/sass/sass/issues/1395#issuecomment-57658736
 @function unicode($str){

sass/partials/_mixins.scss

@@ -1,3 +1,4 @@
+@charset "utf-8";
 // Mixin for handle fallback support for transform-rotation
 // We use it to rotate the degrees of the wind icon
 @mixin wind-rotate($degrees) {

sass/partials/_variables.scss

@@ -1,3 +1,5 @@
+@charset "utf-8";
+
 // Base Variables
 $weather-icons-path:          "../font";
 $WeatherIconVersion:          "1.3.0";

sass/weather-icons.scss

@@ -1,4 +1,5 @@
 @charset "utf-8";
+
 // Import varables and mixins
 @import "partials/variables";
 @import "partials/functions";