Over the last few years I have been wanting to visit the Monarch Grove Butterfly Sanctuary located in Pacific Grove, CA. The migrating season for the butterflies is between October and end of February, being near the holiday season it was always hard to make it out. But this last week I was able to slip away on a most unusually warm winter days in Northern California. It was in 70's which made it warm enough for the butterflies to really flutter around. They looked like tissue confetti being tossed around between the trees. I would suggest bringing binoculars since the cluster together high on the tree tops.
I was able to catch this image of 2 butterflies warming in the sun. :)