You can hard code the title. Getting an option to change the title in the admin interface is a bit more work.
Open myweather.php in any editor and scroll to the very bottom where the widget code is. Copy this
function widget_myweather($args){
extract($args);
echo $before_widget . $before_title;
?>The Weather<?
echo $after_title;
wp_myweather();
echo $after_widget;
}
The Weather can be whatever title you want.
