The mechanism to determine the correct UTC time offset is a bit complicated. First the openweathermap.org API finds the coordinates to a given location and then the worldweatheronline.com API delivers the UTC offset to given coordinates. Of course I use the free developer pricing plan which allows some few API calls per day or per month.
Since 2 weeks my ForEx display didn't worked anymore. Soon I realized how much I rely on that gadget in my daily work. A quick check showed that the worldweatheronline.com API didn't work any more. Well using free API bears that risk as we are aware all of us. But worldweatheronline.com stopped that free offer without any notification mail or similar. That's pretty poor and if they deal like that, I seriously would think twice before using that API for a commercial application.
However I found the timezoneDB.com. It's free and unlimited, only for commercial usage a premium plan needs to be paid. This works fine but due the "one call per second" limitation the initial phase takes a bit longer as there are 7 API calls and a delay() call is require to prevent an API blockage with fast internet access.
The updated code is stored on Github