I think there’s a larger picture at play here that is being missed.
Getting the weather is a standard feature for years now. Nothing AI about it.
What is “AI” is, Hey Siri, what is the weather at my daughter’s recital coming up?
The AI processing, calculated on-device if what they claim is true, is:
the determination of who your daughter is
What is a recital? An event? Are there any upcoming calendar events that match this concept?
Is the “daughter” associated with this event by description or invitation? Yes? OK, what’s the address?
Submit zip code of recital calendar event involving the kid to the weather API, and churn out a reply that includes all this information…
Well {Your phone contact name}, it looks like it will {remote weather response} during your {calendar event from phone} with {daughter from contacts} on {event date}.
That is the idea between on-device and cloud processing. The phone already has your contacts and calendar and does that work offline rather than educating an online server about your family, events and location, and requests the bare minimum from the internet, in this case nothing more than if you opened the weather app yourself and put in a zip code.