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A number of brightly colored monarch butterflies in hues of orange and yellow against a bright blue backdrop
Monarch butterfly photos flying in the sky near Santa Cruz, California, during migration. (Mark Miller Photos/Getty Images)

Where Can I See Monarch Butterflies in California This Winter?

Where Can I See Monarch Butterflies in California This Winter?

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Update, 11:30 a.m., Jan. 31

Citizen scientists and volunteers have counted over 233,300 monarch butterflies across the western United States as part of Xerces Society’s 27th annual count.

This total, calculated from Nov. 11 through Dec. 3, 2023, is slightly lower than last year’s count — and remains at just 5% of their numbers from the 1980s when the monarch population was in the millions. But it is far better than 2020’s record-low count of just 2,000 butterflies or 2021’s meager 29,000.

Despite ongoing efforts to save the butterflies, western monarchs face a decades-long severe decline. “A lot of insect loss — not just for monarchs — is linked to habitat loss, and part of the solution is widespread rewilding and habitat restoration,” said Emma Pelton, a monarch conservation biologist with the Xerces Society.

The use of pesticides, disease and a changing climate may also have contributed to the decline in monarch butterflies, Pelton said.

Over 400 volunteers and partners participated in the annual Thanksgiving count coordinated by the Xerces Society. “Volunteers and partners are the heartbeat of the Western Monarch Count community science effort,” said Isis Howard, who coordinates the count for the Xerces Society. “They embody a collective commitment to the conservation of western monarch butterflies.”

Read more about volunteering for the monarch butterfly count.

Original story from Nov. 3, 2023, continues:

Fall and winter are when western monarch butterflies get all the spotlight here in California.

In the fall, these brilliant fluttering insects in hues of orange and black make their way from west of the Rocky Mountain Range to the many overwintering sites in coastal California. Our coastal forests provide a mild seaside climate and suitable microhabitat for them to cluster to stay warm before leaving again in early spring.

The annual monarch butterfly migration cycle is one of the most spectacular events in the insect world. Western monarchs usually start showing up here in coastal California right around mid-October. This year, some of the very first clusters were reported at the very beginning of October — which is a little earlier than in the past few years, according to Emma Pelton, a conservation biologist at Xerces Society, a wildlife organization.

“In really warm fall years, we see later aggregating and clustering,” Pelton said. But because the Pacific coast has had more “chaotic weather patterns” in recent years due to climate change, she noted, it’s not always easy to predict precisely when the monarch clustering will occur. And it’s local weather conditions that really drive a lot of these butterflies to cluster or then break up, Pelton said.

Monarch butterflies (Danaus plexippus) resting on a tree branch in their winter nesting area. Taken in Santa Cruz, California. (GomezDavid/Getty Images)

Where to see monarchs near the Bay Area

Coastal groves and eucalyptus trees provide a temperate and protected environment for the butterflies during their hibernation. So, if you want to see their bright colors, you’ll want to head south on Hwy 1 from the Bay Area.

A few places in California where monarchs frequently find refuge in colder winter months:

Some lesser-known sites in Alameda county in the Bay Area where monarchs have been seen in the past include:

Xerces has a map of all the monarch butterfly overwintering sites in California, but note that some of these locations might not be open to the public.


Western monarch numbers over the years

Related coverage

In the 1980s, over 4 million western monarch butterflies migrated to the coast annually. But by the mid-2010s, the population had declined to around 200,000 butterflies.

In both 2018 and 2019, volunteers counted under 30,000 monarchs. That downward pattern continued in 2020, when volunteers counted a record low of less than 2,000 monarchs, according to Xerces.

Some good news, however, has come in more recent years. In 2021 and 2022, the numbers went back up to around the 300,000 mark.

“I think this has inspired a lot more hope that the migration can be saved. And we need to double down on our conservation actions,” said Pelton, with the Xerces Society.

Reasons like habitat loss, use of pesticides, disease, and a changing climate may have contributed to the decline in monarch butterflies.

How can I help monarch butterflies?

The easiest way to get involved is to log your monarch sightings.

When you see a monarch, Pelton encourages folks to record that on community science applications like iNaturalist. Not only that, you can also help by logging sightings of milkweed, the plant monarch butterfly’s need for their caterpillars. The data from iNaturalist feeds into the Western Monarch Milkweed Mapper, which is used by researchers in the monarch world to “understand where and when butterflies are, where and when milkweed is,” Pelton said.

Another way people can help with monarch butterfly conservation is by planting more native milkweed in their home gardens or neighborhoods, like in community gardens, schools or at places of worship. “I think everyone has a role in planting nectar plants that support monarchs,” Pelton said. Through programs like the Xerces Habitat Kit, folks can apply for free native milkweed and other host plants for other butterflies.


One thing to note: Pelton advises avoiding the tropical milkweed species Asclepias Curassavica. Tropical milkweed can potentially interrupt monarch migration and help spread disease caused by a parasite called Ophryocystis elektroscirrha, or OE.

There’s increasing evidence showing that pesticides may be contributing to the declining monarch populations, Pelton said. This means that thinking about ways to lower our reliance on pesticides in general, both in our agricultural and urban areas, can be a significant way to support the habitat for monarchs.

Pelton advocates for focusing on “the bigger picture issues like climate change policies, pesticide regulation and registration — things that support wildlife, native plants, and native habitats on our landscape.”

How can I take part in the annual Thanksgiving and New Year’s count of monarchs?

Peak numbers for monarch butterflies begin in November — which is also the time when Xerces conducts their annual Thanksgiving monarch count.

This year will be the 27th annual Western Monarch Count, and volunteers can take part between Nov. 11 and Dec. 3 during the Thanksgiving count and again between Dec. 23 and Jan. 7 during the New Year’s count.

You can sign up to join a free training on Nov. 4. You’ll also have access to online training videos.

Next step for conservation enthusiasts

Pelton hopes that some of the excitement around western monarch conservation can spread to other insects that are maybe less beloved. “I like to think of monarchs as a little bit of a Trojan horse,” she said. “We’re going to get people hooked, and then really we’re going to get them into all these other conservation [efforts].”

Like the conservation of California’s beautiful black and yellow bumble bees, for example. The California Bumble Bee Atlas is a community science effort to track and conserve the species, which Pelton calls “big, fuzzy, beautiful.”

“They have very clear patterns on them,” she said — and it doesn’t take a ton of training or time to start to be able to identify individual species of the bumblebee.

The biodiversity crisis and how that intersects with the climate change crisis is something that we also all should be thinking about, Pelton said.

“Habitat is just one of those really great ways where we can tackle the problem — by creating refuges and creating a diversity of habitats [wildlife] can use, so they can adapt in a changing climate,” she said.


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