Monarch Butterfly Migration California 2024 Dates. During the summer, it inhabits the pacific northwest, including states like oregon, washington, nevada, and idaho. In the 1980s and '90s, more than a million made the trip.

Help us track monarch migration and the presence of milkweed. Each year, from october through early march, monarch butterflies migrate to central and southern california, traveling from areas west of the rocky mountains and south of oregon and idaho.