Agreed - if I had asked for the weather in Sao Paulo, and it gave me the weather for Sao Paulo on Sunday night, I would be frustrated rather than impressed.
The app is making the implicit assumption that I didn't know what I really wanted, and correcting me. Rather than desirable, I find this creepy, incorrect behaviour and potentially offensive.
While I agree with you on all parts, a cynical side of me tells me that assuming that a majority of your users doesn't really know what they want (or less condescendingly: make assumptions they are not fully aware of) is a viable strategy.
The app is making the implicit assumption that I didn't know what I really wanted, and correcting me. Rather than desirable, I find this creepy, incorrect behaviour and potentially offensive.