Seeing monarchs in Pacific Grove depends mostly on the weather of the past week and on knowing which edge of the grove to check. The calendar matters less. Last winter, the city's consulting biologist logged 203 butterflies at the Monarch Grove Sanctuary on January 17. Three weeks earlier, after one Christmas windstorm, the count was 3. In between, the count rose to 131, fell to 25 during a second windy stretch, and recovered. The same grove and the same season produced all of those numbers, and in Weiss's account the wind drove the swings.
That pattern comes from the city's own report for this year: Assessment and proposed management activities Monarch Grove Sanctuary and George Washington Park for 2026, written by Stuart B. Weiss of Creekside Science. Most monarch coverage stops at "arrives in October, leaves in February." The report goes further and records which trees the butterflies chose, which edge of the grove they stayed on, and what moved them.
The Grove Is Still Empty
As of early October, the sanctuary is waiting. The Pacific Grove Museum of Natural History last updated its season page on 9/19/26. At that point no monarchs had arrived, and the butterflies were still in their northern grounds in inland California and the Pacific Northwest. The Museum expects them to start arriving in a slow trickle in mid-October, with the peak around the end of November. It posts a weekly count once the butterflies begin settling.
Last season followed the same timing. Weiss records monarchs arriving in small numbers in mid-October 2025 and reaching 188 by mid-November. If a walk past the sanctuary on Ridge Road turns up nothing this week, the season is simply running on schedule.
Two Winters on the South Edge
Over his years of monitoring, Weiss has seen the butterflies use eucalyptus, Monterey pine, and cypress in mixes that shift "from week to week and year to year." The last two seasons were steadier. In 2025–2026, they clustered in the sunny areas along the South and Southwest Edge and stayed there all season. Of his observations, 94% were on eucalyptus, 5% on pine, and 2% on Monterey cypress. He describes 2024–2025 as a similar pattern.
The report also explains why other years looked so different:
Preferences for pines and cypress in most years season is the result of the windsheltered interior being dominated by pines and cypress, not an intrinsic preference for those species.
The trees the monarchs use follow from wind shelter, not species. In 2023–2024, the clusters moved from the South Edge into the South Interior by mid-November, into the Interior in early January, and to the Driveway in February. In 2022–2023, a series of strong storms pushed them all the way into the North Interior. Weiss also notes that they have often clustered just outside the sanctuary to the south, on a single isolated Monterey pine, and that they hang on lace lichen in the interior.
He sums up the mechanism as monarchs that "crowdsource the microclimate." They leave spots that are too warm, too cool, too sunny, too shady, or above all too windy, and they land where other monarchs are already clustered, since the presence of other butterflies is the best sign that conditions are good. Clusters usually start the season on the sunny South Edge and move inward after southerly storm winds.
That gives a working rule for this fall. Early in the season, and after a run of calm weather, look along the South Edge eucalyptus. After a southerly storm, look deeper into the pines and cypress.
One Storm, Three Butterflies
Weiss calls 2025–2026 a mild overwintering season. It had one strong wind event, above 25 mph on December 24–25, and one multi-day stretch of moderately strong wind from January 4 to 8. Even in that easy year, the counts swung widely:
- November 21: 188, the figure reported for the official Mid-Season count
- December 12: 226, the season peak
- December 26: 3, the day after the Christmas wind
- January 2: 131
- January 7: 25, during the January wind
- January 17: 203
- February 7: emigration complete
The quick rebound to 131 by January 2 shows that the monarchs "scattered rather than emigrated," in Weiss's words. He adds that widely dispersed monarchs in small clusters or alone are hard to detect, so the low counts likely undercount them. The cover photo makes the same point, showing silhouetted monarchs on the South Edge as "an example of how difficult it can be to find small numbers among the trees."
A thin morning in December after a windy night does not mean the season is over. Last winter, the count had climbed back to 131 within a week of the Christmas wind. Warmth, not wind, ended the season. Late January brought seven days above 70°F, and the monarchs left the grove during a stretch of high-70s temperatures.
The Two Counts, in Statewide Context
Pacific Grove's 188 from the Thanksgiving count is the number the Xerces Society published for the sanctuary. Statewide, the 2025 Western Monarch Count recorded about 12,260 monarchs at 249 sites, the program's third-lowest total since 1997. Weiss puts that total next to 9,119 in 2024, an increase of roughly 33%. He also sets it against the population's rebound to between roughly 233,000 and 335,000 in the seasons after 2020, and calls the gain encouraging but "well within the typical fluctuations."
At the federal level, the U.S. Fish and Wildlife Service said in its September 21, 2026 update that the monarch is not federally protected and that the proposed threatened listing has had no final ruling yet. The Museum describes the sanctuary as the largest overwintering site for monarchs in Monterey County. With numbers this low, the South Edge cluster carries more weight for the region than its size suggests.
What the City Was Advised to Do Before They Arrive
The 2026 report draws on site visits through last season and on consultations in January and early June 2026 with new City Arborist John Kelly and environmental manager George Fuerst. Weiss calls for "relatively little management" this year. His main short-term recommendations are:
- In September, remove and spread out downed bark, branches, and leaves along the South Edge to reduce fire hazard. Leave some debris, broken up by fuel breaks several feet wide, so grounded monarchs can climb off the forest floor.
- Remove hazard trees and branches as they are identified.
- Bring the large fallen tree in the interior down to the ground and break up piles of fine fuel.
- Pause new tree planting, with one exception: a double row of cypress along the hotel boundary in the northeast corner.
- Thin overly dense trees, including the planted cypress northeast of the nectar beds.
- Cage the oaks along the west boundary to protect them from deer, and keep managing the nectar beds.
These are recommendations, and the report does not confirm what has been finished. For the prior year, Weiss records that dead small trees in the southeast corner were removed but that the recommended rearrangement of debris around the large eucalyptus did not happen. The South Edge debris work matters because the South Edge is where the butterflies have spent the last two winters. The report includes a photo of a eucalyptus trunk scorched in a small fire on March 31, 2024.
Hours, Docents, and This Weekend
The sanctuary is open from sunrise to sunset every day. Entry is free, the site is ADA accessible, free street parking is limited and includes Lighthouse Avenue, and buses cannot park there. Museum docents are generally on site October through February from 11 a.m. to 3 p.m., weather permitting. Volunteers can sign up for training, which starts with a virtual session on October 7 and an in-person orientation at the sanctuary on October 10.
The town's welcome went ahead before the butterflies arrived. The Butterfly Parade stepped off at 10:30 a.m. on Saturday, October 3, with a bazaar at Robert Down Elementary School afterward. Butterfly Days Weekend runs through today, October 4. Its program included a birdhouse silent auction at Chautauqua Hall, a croquet tournament at Caledonia Park, and a sunset celebration at Point Pinos Lighthouse with the David Holodiloff Trio.
The Museum's weekly count is the next update to watch, starting once the first butterflies settle in mid-October. Until then, the South Edge eucalyptus are the trees to check, and after the first southerly storm, the interior pines.
Cheryl Heyermann has spent decades watching how setting, light, and shelter shape the homes around Pacific Grove. If you'd like to talk about a property near George Washington Park or the sanctuary, or anywhere else on the Peninsula, Bramin Atler is glad to help. Let's Connect.
