Answer:
This could be taken as irony.
Step-by-step explanation:
A wedding day is suppose to be happy and filled with joy. A sunny day would represent this, thats why people say "it was like a sunny day". Whereas rain is referred to sadness and depression, like a funeral. So in this case it would be ironic for a wedding say to be compared to the emotions of sadness and depression.
Hope this helps (: