Migration of the monarch butterfly

So I'm probably late to the party, but I just heard about the impressive migration of the monarch butterfly and I'm thinking that it'd be interesting to photograph. From the maps I've seen they basically fly over the entire USA, but maybe someone on this forum can help me narrow it down. Are there specific areas and periods where one is more likely to see swarms of butterflies cloud the sun?

I used to live in Santa Cruz, California, and the monarchs breed there at Natural Bridges State Park. You could see quite a lot of them flying around if you went at the right time, but I don't recall seeing them cloud the sun.

Slight hyperbole .

Around what time did you tend to see them? Did they really cover trees completely as I've read, or was that hyperbole too?

armis wrote in post #15971482
Slight hyperbole .

Around what time did you tend to see them? Did they really cover trees completely as I've read, or was that hyperbole too?

They live in Santa Cruz during the winter. There are a lot of them there, and it is very colorful and impressive. The park's website has some more specific info about when to catch them:

http://www.parks.ca.go​v/?page_id=541

Much obliged!