Last winter's official Thanksgiving number for Monarch Grove Sanctuary was 188 butterflies, counted on November 21, 2025. Three weeks later, on December 12, the grove peaked at 226. Both figures come from the City of Pacific Grove's 2026 Monarch Grove Sanctuary review, the yearly habitat assessment for the grove on Ridge Road. Read it before the butterflies settle in and it shows two things about the season ahead. The grove's best weeks tend to come after the date everyone watches, and the butterflies gather on one narrow edge of the forest. That edge is also where the review recommends the most work this year.
Last Winter, Read Week by Week
The review uses weekly monitoring data that the Pacific Grove Museum of Natural History has collected since 2013. That record shows a season that is more uneven than one Thanksgiving number can capture.
| Date, 2025–26 season | What happened at the grove |
|---|---|
| Early October 2025 | Monarchs arrive and cluster on the sunny south and southwest edge |
| November 21, 2025 | Official mid-season count: 188 |
| December 12, 2025 | Season peak: 226 |
| December 24, 2025 | Brief drop in numbers after a high wind event |
| January 9, 2026 | Another brief drop after high winds |
| Early February 2026 | Monarchs have left the grove |
According to the review, both winter dips recovered to their pre-wind numbers. A thin count right after a wind event said more about the weather than about the season.
The comparison year makes the local picture clearer. Pacific Grove's mid-season count fell from 228 in 2024 to 188 in 2025. Across California, the Xerces Society's 2025 results, released January 29, 2026, went the other way. The society counted 12,260 western monarchs at 249 sites, up from 9,119 in 2024, though Xerces still called it the third-lowest total in the count's history. The same release lists 188 monarchs at the Pacific Grove sanctuary. In other words, the state recovered a little last year and the grove on Ridge Road did not.
One Edge, Mostly Eucalyptus
After arriving in early October, the butterflies stayed on the south and southwest edge for the whole season. The review logged 94 percent of observations on eucalyptus, 5 percent on Monterey pine, and 2 percent on Monterey cypress.
So the grove's native trees host almost none of the clusters. "This is not a 'natural' forest," the review says. It argues that the non-native eucalyptus, including a shelterbelt planted in 1999, provides the wind protection and moderate light that bring monarchs in and keep them there, so those trees should be maintained. The grove you walk through is shaped on purpose, and the people shaping it work from a written plan that dates back to a 2011 management plan, with annual recommendations from 2014 onward.
Why That Same Edge Tops the 2026 List
The south edge holds the butterflies, and it also collects the most eucalyptus bark, branches, and leaves. The review's first recommendation for 2026 is to remove and redistribute that debris along the South Edge in September, especially where it has piled up against the trunks. It suggests leaving some debris in place with fuel breaks several feet wide, so a monarch that falls to the ground can still climb back up. It also recommends making this an annual job that starts each spring. The cover photo on the review shows a eucalyptus trunk scorched in a small fire on March 31, 2024, which is the reason it gives for clearing ground fuels.
Beyond that first item, the review calls for "relatively little management" in 2026. Some of the items:
- Remove hazard trees and branches as they are found.
- Bring the large fallen tree in the interior down to the ground and break up the piles of branches and needles.
- Pause new tree planting, with one exception. A double row of cypress would go along the property line with the hotel in the northeast corner.
- Thin overly dense trees, including the planted cypress northeast of the nectar beds and the crowded eucalyptus in the southeast corner.
- Cage the oaks along the west boundary against deer.
- Manage the nectar beds and rethink irrigation, including deeper, less frequent watering at George Washington Park.
The southeast stand was planted in 2013, and after 13 years of growth the review describes it as crowded, with some trees already dead, so selective thinning there is meant to give the remaining trees more light and water.
Some of the work carries over from earlier years. The 2025 plan's dead-tree removal in the southeast corner and its stake removal were completed, and no new trees were planted. The forest-floor debris work around the large eucalyptus is back on this year's list. As of October 11, 2026, we have not found any public report confirming whether the September clearing on the south edge was done. On your first visit this season, the ground beneath the clustering trees is the easiest place to see whether it happened.
The 2026 Season, As It Arrives
The Pacific Grove Museum's monarch page was last updated September 19, 2026. At that point no monarchs had arrived, and the museum expected a slow trickle starting in mid-October with peak numbers around the end of November. That forecast lines up with an average year. Last year's peak came in mid-December, so the museum's weekly updates, which begin once the butterflies settle, are the best way to tell which kind of year this is. The City's sanctuary page also sends visitors to the museum for weekly counts.
The statewide count runs on its own schedule, published by the Western Monarch Count:
- Early season: October 17 to November 1, 2026
- Mid-season (Thanksgiving): November 14 to December 6, 2026
- Late season: December 26, 2026 to January 10, 2027
The late-season window falls around the same days as last winter's wind dips. That makes it a useful check on whether the grove holds its numbers into January.
Getting there
- Address: 250 Ridge Road, Pacific Grove. Street parking is limited, including on nearby Lighthouse Avenue.
- Approach: From Lighthouse Avenue, turn onto Ridge Road. The sanctuary path runs beside the Butterfly Grove Inn property.
- Hours: Sunrise to sunset every day. The grove closes only when extreme weather makes visits unsafe.
- Docents: Usually on site from 11 a.m. to 3 p.m., weather permitting, October through February.
- Family day: The museum's free Science Saturday, "Monarch Magic!", runs Saturday, November 28, 2026, from 10 a.m. to 3 p.m. at the museum.
The Other Grove in Town
Monarch Grove Sanctuary is one of two sites in town. The City describes George Washington Park as part of Pacific Grove's original overwintering habitat. It says the park's habitat has declined because of urbanization, aging trees, and environmental stress, and that it is now being restored with new planting, mulching, and trail improvements. The irrigation change in the 2026 review, deeper watering spaced further apart, applies to that park. Both sites depend on trees being managed for wind shelter and light, and both are being worked on now.
This year's Butterfly Parade went down Lighthouse Avenue on Saturday, October 3. It came before the butterflies did. Going by last winter's record, the grove is likely to be fullest weeks after Thanksgiving, on the eucalyptus along the south and southwest edge, if the trees there make it through another winter of wind.
When you visit the grove this season, you're also seeing a stretch of Pacific Grove that the Bambace Peterson Team knows street by street. If you have questions about the blocks around Ridge Road or anywhere else in town, contact us. We're glad to talk.
