The easiest is to use a looping timer set, for example, to 5 seconds and use it to call your REST API. See here: Using Timers | Unreal Engine Documentation
That will update the temperature once every 5 seconds.
I tried adding a timer every 60 seconds to update it by using a set time on function , but it doesn’t work , I put it after initialization and tried to put also on consctruct but nothing changes the values.
You should set a Timer by Event and have it call a custom event (e.g. TimerCall), then use that custom event to call the REST API (Call URL) and finally the Callback is the event Risposta Temp&Umid you already have.
Nope. You are calling a custom event like it would be a function, but it is not. That’s why it doesn’t work. Use Set Timer by Event and link it to a custom event which calls your Call URL.