Pacific Grove's Monarch Season Comes Down to One Edge of One Grove

Walk into the Monarch Sanctuary off Ridge Road this week and look up into the middle of the grove, and you'll probably see branches with no butterflies on them. Last season they gathered somewhere much more specific. They arrived in early October and clustered in the sunny areas along the grove's south and southwest edge, and they stayed there until they left in early February. Over the whole season, 94% of observations were on eucalyptus. Monterey pine accounted for 5% and Monterey cypress for 2%.

Those numbers come from the City of Pacific Grove's 2026 Monarch Grove Sanctuary review, written by consultant Stuart B. Weiss, who has worked at the sanctuary since 1997. Together with an Oct. 20 city commission meeting and an Oct. 21 City Council packet, the review shows how narrow Pacific Grove's monarch season really is. Most of what the town calls "the monarchs" happens on one strip of trees, and the city now schedules a good share of its tree work around keeping that strip usable.

Where the season stands as October ends

It has been a slow start. At the Pacific Grove Beautification and Natural Resources Commission meeting on Oct. 20, Environmental Program Manager George Fuerst reported that Pacific Grove Museum counters had seen up to two monarchs at a time at the sanctuary. He mentioned "a handful" of sightings around town and said neighboring overwintering sites in Santa Cruz and down the coast had started to see more. At the same meeting, one commissioner said they had seen a monarch in their garden the day before but none at the sanctuary the week before.

None of that is unusual for the calendar. The Pacific Grove Museum of Natural History says monarchs typically arrive in mid-October and leave in February, and it expects this season's population to peak around the end of November. The museum's advice for early-season visits is to come in the afternoon, when the few butterflies already here flutter around the nectar beds in the lower part of the sanctuary.

Here's how last season compares with the wider count:

Pacific Grove's peak of 226 is small next to Natural Bridges, and the Xerces Society describes western numbers overall as remaining at a historic low. Weiss calls the roughly 33% increase over 2024 encouraging but within typical fluctuations, and he says the western population is still at perilously low numbers. With so few butterflies spread across 249 sites, it becomes very important which trees inside any one grove actually get used.

Why the south edge, and what wind does to it

The pattern held all season long. After arriving, the butterflies settled on the sunny south and southwest edge, almost entirely on eucalyptus, and they were still there months later.

The review also tracks what happened when the weather turned. Numbers dipped sharply twice, around Dec. 24 and Jan. 9, after high wind events, and then recovered to pre-wind levels. So the cluster you see one afternoon can thin out after a blustery night and fill back in within days. It's one reason the museum suggests checking its monarch page or calling before a visit. High winds are also the one condition that closes the sanctuary itself. It's an open park, open sunrise to sunset every day including holidays, and it closes only when extreme weather would make a visit unsafe.

For a resident's walk this season, that turns into a short checklist:

1. Go in the afternoon while numbers are low. The nectar beds in the lower sanctuary are where the museum says the early arrivals show up.
2. Look along the south and southwest edge once clusters start forming, and look at the eucalyptus first.
3. Wait a few days after a windstorm if the branches look empty. Last season's dips recovered both times.
4. Time a visit for docent hours. The museum lists docents as often present from October through February, generally 11 a.m. to 3 p.m., weather permitting.

A grove managed around one strip of trees

Because the butterflies concentrate where they do, the city's annual recommendations focus on the trees around them. The 2026 review covers site visits through the 2025–26 season plus consultations with new City Arborist John Kelly and George Fuerst in January and early June 2026. Weiss describes the 2026 plan as "relatively little management." Among its main recommended actions:

• In September, remove and redistribute downed bark, branches and leaves along the south edge, leaving some debris so a monarch that falls has something to climb off the ground on.
• Pause new tree planting, with one exception: a double row of cypress along the property boundary with the hotel in the grove's northeast corner.
• Thin overly dense trees, especially the planted cypress northeast of the nectar beds, and keep removing dead and sickly trees from the dense eucalyptus stand in the southeast corner.
• Cage oak trunks along the west boundary to protect them from deer, and plan replacements for poor-performing plants in the nectar beds.

The review also reports which of the 2025 recommendations got done. Dead small trees came out of the southeast corner, stakes and wires were removed from saplings where appropriate, the remnant pine trunk along the main path was removed, and no new trees were planted, as recommended. The suggested rearrangement of forest-floor debris around the large eucalyptus was not done.

The 2026 recommendations are written as a plan, and the public record doesn't list item by item what was finished this fall. At the Oct. 20 meeting, one commissioner described a walkthrough of the sanctuary with George Fuerst as "really impressive" and said, "They've done a lot of work to get that ready."

The other grove that sits empty

George Washington Park is a 20-acre forested park that runs from Short Street to Sinex Avenue between Melrose and Alder streets. It has trails, picnic areas, a playground and a baseball field. The city's draft forest management plan for the park, included in the Oct. 21, 2026 City Council agenda packet, calls it one of the few remaining native-tree habitats for overwintering western monarchs. It also states plainly that monarchs have not overwintered there in substantial numbers since 2006. The Thanksgiving count recorded zero there in both 2024 and 2025.

Set the two sites side by side and the season's geography gets clearer. The park with the native trees has been mostly empty for two decades. The sanctuary's eucalyptus edge holds almost the whole local population. Even so, a 2024 biological resources report cited in the plan found that George Washington Park could support overwintering monarchs again and has a high potential for future occurrence. The Weiss review backs that up with a specific recommendation: water the park's young pines more deeply and less often.

The park also shows how tightly the city's calendar is set around the butterflies. The September work there included mowing and low-limb removal near homes, taking out dead or hazardous trees or leaving some as wildlife snags, and clearing the main trails. When a commissioner asked at the Oct. 20 meeting whether it was finished, the answer was that it had "concluded for this year." The crews had a one-month window that started after bird nesting season, when a bird survey would have been required, and closed before monarch overwintering season began Oct. 1. The packet sets that same September 1 to 30 window as the plan's primary work period, because it falls outside monarch overwintering, nesting bird season and bat maternity season.

The dates to hold through January

The Xerces Society's Western Monarch Count runs volunteer surveys in three windows. When this post publishes on Thursday, the early-season window is still open.

• Early season: Oct. 17 to Nov. 1, 2026
• Mid-season, the Thanksgiving count: Nov. 14 to Dec. 6, 2026
• Late season: Dec. 26, 2026, to Jan. 10, 2027

On Saturday, Nov. 28, the museum holds "Science Saturday: Monarch Magic!" from 10 a.m. to 3 p.m., with activities on the monarch life cycle and habitat and free museum admission. That lands right around when the museum expects the population to peak. The museum is at 165 Forest Ave. and open Wednesday through Sunday, 10 a.m. to 4 p.m. Regular adult admission is $15, and Monterey County residents get in free with valid ID. The sanctuary is at 250 Ridge Road, and on a warm afternoon the eucalyptus along its south edge is the first place to look.

I grew up watching this grove go through its seasons. If you're weighing a home near the sanctuary or George Washington Park and want to know how these woods change through the year, Ben Ottmar is happy to walk you through it. Get in Touch.