Wt

Would this be the preferred method?

WLocalDateTime local_datetime;

local_datetime.setDateTime(WDate(2020, 05, 28), WTime(15, 30, 0));

WDateTime utc_datetime = local_datetime.toUTC();

That should work if the current locale is set to the right timezone. You can set it like this:

locale.setTimeZone(date::locate_zone(timeZoneName));

On Linux that should just work, because it comes with its own copy of the IANA time zone database. On Windows, there is a time zone database, but it is not compatible with our implementation. You'll have to download the time zone database instead: https://www.iana.org/time-zones. There are some more details in the locale feature example: https://github.com/emweb/wt/tree/master/examples/feature/locale