"Museum counters saw up to two monarchs at a time."
City staff gave that report at Pacific Grove's Beautification and Natural Resources Commission meeting on October 20. At the same meeting, one commissioner said she had seen a monarch in her own garden the day before but none at the sanctuary the week before. As of October 30, the Pacific Grove Museum of Natural History still described the butterflies as arriving and expected the population to peak around the end of November.
For anyone who lives a few blocks from Ridge Road, the useful fact is that a small population sits in a predictable part of the grove. The city's 2026 habitat assessment, written by ecologist Stuart B. Weiss, tracked where the butterflies sat through all of last winter. The answer was almost always the same edge and the same kind of tree. When the grove did look empty, the butterflies had mostly scattered, not left.
Two seasons on the same sunny edge
In the 2025–26 season, monarchs reached the Monarch Grove Sanctuary in early October and settled in sunny spots along the South and Southwest edges. They stayed there all winter. Only a few moved into the South Interior, just north of the main trail, and those sat on pines.
| Tree type, 2025–26 season | Share of monarch observations |
|---|---|
| Eucalyptus | 94% |
| Monterey pine | 5% |
| Monterey cypress | 2% |
The 2024–25 season followed nearly the same pattern. The 2023–24 season, the last big year, did not. That winter the butterflies started on eucalyptus, moved mostly to pines, and ended on cypress. They worked from the South Edge into the South Interior by mid-November, reached the Interior in early January, and gathered along the Driveway in February. Advice from someone who remembers that year may send you to the wrong part of the grove.
The assessment also notes that monarchs have often clustered just south of the sanctuary boundary, on a lone Monterey pine.
Why small numbers are harder to see
Weiss writes that monarchs "crowdsource the microclimate." They leave a spot that turns too warm, too cool, too sunny, too shady or too windy, and they land where other monarchs already hang, because other butterflies are the best sign that conditions are right.
In a big year, that habit creates heavy clusters you can spot from the path. In a thin year, the clusters stay small. The cover of the city's report shows monarchs as silhouettes on the South Edge, with a caption about how hard it can be to find small numbers among the trees. A closed monarch with folded wings looks a lot like a dead leaf hanging from a eucalyptus branch.
Timing helps. The museum says afternoon visitors will see monarchs flying around the nectar beds in the lower part of the sanctuary. Its volunteer docents are usually at the sanctuary from 11 a.m. to 3 p.m., October through February, weather permitting, and they know which branches the butterflies have been using that week.
What a windstorm did last winter
The edge pattern explains where to look. Last winter's count log explains why an empty grove shouldn't end the visit. Here is how the sanctuary's numbers moved in the 2025–26 season, according to the city's assessment:
| Date | Monarchs counted | What happened |
|---|---|---|
| Mid-October 2025 | Small numbers | Arrival |
| November 21, 2025 | 188 | Official mid-season count |
| December 12, 2025 | 226 | Season peak |
| December 26, 2025 | 3 | Strong wind on December 24 and 25 |
| January 2, 2026 | 131 | Butterflies regroup |
| January 7, 2026 | 25 | Another drop |
| January 17, 2026 | 203 | Recovery |
| February 7, 2026 | None | Departure complete |
Weiss reads the bounce back to 131 as evidence that the monarchs "scattered rather than emigrated." He adds that butterflies spread out in small groups or alone are hard to detect, so some undercounting is likely after a storm breaks up the clusters. In practice, a walk the day after a big blow may turn up very few butterflies, and the same walk a week later may turn up close to the full group again. In earlier seasons, southerly storm winds pushed the butterflies off the South Edge and into the interior, so after a storm it's worth looking deeper in.
The museum says the sanctuary itself closes only in extreme weather, when high winds make a visit unsafe.
How thin the recent years have been
The small groups make more sense with the longer record. Monterey County NOW reported that the sanctuary's official count was 188 in 2025, compared with 228 in 2024 and 6,508 in 2023. In the same article, museum education manager Natalie Johnston recalled 2021, when Pacific Grove's numbers jumped past 13,000 a year after a count of zero. She told the outlet that monarch populations can be "bouncy," but that last year the bounce didn't come.
Statewide, the Xerces Society's 2025 count found about 12,260 monarchs at 249 sites between late November and early December 2025. That was the third-lowest total since counting began in 1997. According to the city's assessment, Pacific Grove's sanctuary has held an average of 7% of California's mid-season count since 1999. Last season it held 1.5%, ranking 16th in the state. Most of Monterey County's monarchs that season wintered at a private site near Big Sur, Esalen.
What the city did before October 1
The city fits most grove maintenance into the weeks before the overwintering season starts. At the October 20 meeting, one commissioner said several members had walked the sanctuary with environmental manager George Fuerst and that the city had done "a lot of work to get that ready." Fire-fuel reduction at George Washington Park, which the city counts as part of Pacific Grove's original overwintering habitat, finished for the year in the window between bird nesting season and the October 1 start of the monarch season.
For the sanctuary, Weiss recommended relatively little for 2026. His list included clearing and spreading out eucalyptus bark and leaf debris along the South Edge, removing hazard trees as they are found, pausing new tree planting except for a double row of cypress along the hotel boundary in the northeast corner, and managing the nectar beds. The South Edge, where the debris work was aimed, is the same strip where the butterflies spent the last two winters.
The weeks ahead
The peak window is about to open:
- Saturday, November 14, through Sunday, December 6: The Western Monarch Count's 2026 mid-season count, formerly the Thanksgiving count. Volunteers will tally sites up and down the coast.
- Late November into early December: In past seasons, the sanctuary's numbers have peaked during this stretch, according to the city's assessment.
- Saturday, November 28, 10 a.m. to 3 p.m.: Science Saturday: Monarch Magic! at the Pacific Grove Museum of Natural History. Admission is free, with live music by the 5 M's, pollinator and habitat activities, and a monarch-migration game.
The sanctuary at 250 Ridge Road is open from sunrise to sunset every day, including holidays. Admission is free and no reservation is needed. The packed gravel trail is ADA accessible, with a slight downhill slope. Pets are not allowed. Street parking is free but limited, on nearby streets like Lighthouse Avenue. If you're bringing holiday guests, plan an afternoon visit on a calm day, head for the eucalyptus along the South Edge, and check the nectar beds below on your way out.
At Homes by Henson, we've watched families take visiting relatives down to the grove year after year, and walks like that are part of what home means for our Pacific Grove clients. If you're thinking about what your place near Ridge Road might be worth, or you're handling a family property in town from out of the area, we're glad to talk it through. Book a free home valuation whenever you're ready.
