Current week is a simple and easy to use app that shows the week number for the current week. You can also find out the current week number from a specific date. The app includes a home screen widget that displays the week number to. There is also an Apple Watch app available with a complication so you can see the current week number right from the watch face.

The app uses the current date on the device to get the current week number so it should work in all timezones.