From: Rui on
As one simple concrete example, when I put
WeatherData["Buenos Aires", "Humidity", "DateValue"]
I'm getting {{2010, 5, 10, 16, 0, 0}, 0.486}
and it's still 14:15 pm of that day.
$TimeZone gives -3 which is correct.
I'm not sure if there's a timezone offset to all dates returned by
Mathematica or what is happening...

Thanks