Temperature can have a major effect on the color of a bloom on any plant. Besides orchids, I also grow, extensively, a plant called hippeastrum (commonly and incorrectly known to the general public as amaryllis).
A friend of mine grows the same flower as I called Brendan's Flower and it is a unique and interesting bloom. However, he lives in Phoenix (quite hot most of the year) and I in Denver (can be hot but we always have cool/chilly nights). The color difference can be dramatic with the exact same bloom.
His...
Mine...
Both very beautiful blooms but the temperature difference seems to make a difference in their actual blooms. Our culture is slightly different too but these plants are stable in that they're bulbs and they have what they need at the time of bloom-- fertilizer etc does little to affect the bloom once the plant has begun the process.
Cold temps are definitely able to change the color of the bloom but my thoughts are that it is the temp difference is what does the trick, too (day vs night).
I have had examples of this in orchids, too, but have no photos for evidence. My summer blooms are already pale in comparison to my Winter blooms of the same plants when they on occasion will bloom again in the Summer.