November through January is their peak population. I saw large clusters in November. You can see them in the pictures from my review.
January and February are the best times to see the monarch butterflies at Pacific Grove by Monterey a Natural Bridges in Santa Cruz
January is when they winter.
Late winter to early spring.
Migration is in September...best time.
November to March 1st.
From what I experienced about the end of November to beginning of December. Saw 4 huge clusters when I went the weekend after the Thankgiving holiday.
February 2 yrs ago was solid, rhis year was extremely low! I have yet to visit in the fall but hear good things!
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