WB Hates Whiteys
Auto WB is often 'fooled' by dominant non-target colours in a scene. In the case of the blue-sky background it's trying to neutralise the sky by warming it.
The only time I use Auto now is in mixed artificial lighting. For everything else I pick a particular balance preset (eg Daylight) and stick to it. Resulting colours might be 'off', but at least they're consistently off.
|Meet at HKCC Rain or Shine by pen araneae|
from Your City - Rain Down on Me
|Pregnancy Is Beautiful by sye46|
from Women's World
|Criss-Cross Traffic by PEB|
from Best Use of Motion
|Picking a Star in the Milky Way by vbuhay|
from My Best Photo of the Week