One thing that has tripped me up using Flow to change the time is that when you adjust the time backwards it doesn't change the date when you roll past 00:00 UTC. If the current time is 02:00 UTC on August 23 and you bump the time back 3 hours, you get 23:00 UTC on August 23 instead of 23:00 UTC on August 22. It's easy to roll back past midnight end up with a time in the future, which would mean that Live Weather doesn't work.