Monarch butterflies in 2025-2026: the official count of 2.93 hectares, and the seasons before it

On March 17, 2026, in Mexico City, the environment ministry (SEMARNAT) and the protected-areas commission (CONANP), with WWF Mexico, presented the results of the 2025-2026 monarch butterfly overwintering season: the colonies in the forests of Michoacán and the State of Mexico covered 2.93 hectares, 64% more than the 1.79 hectares of the season before. It is the official measure of the colonies visitors travel to see, and CONANP said it showed the recovery continuing for a second year in a row.

What the figure measures

The count is the area of forest covered by the clustered butterflies, in hectares. CONANP described the method in 2022: from December 2021, the 13 overwintering sanctuaries of the Monarch Region were visited twice a month, each colony was located by GPS, and the perimeter of the occupied forest was traced from tree to tree. For 2025-2026, the main measurements were taken in the second half of December 2025, and two of the colonies were recorded in January 2026. Monitoring covered 13 sanctuaries and also drew on satellite images and geospatial analysis, which will serve to check the health of the oyamel fir forest, SEMARNAT's head, Alicia Bárcena, said.

The butterflies travel more than 4,000 kilometers from Canada and the United States to Mexico, Bárcena said. Each weighs less than a gram, according to the Commission for Environmental Cooperation (CEC), an intergovernmental body set up by Canada, Mexico and the United States. The CEC says a single generation, living up to nine months, makes the journey south, while the return north takes four generations.

Where the 2025-2026 colonies were

CONANP counted nine colonies: three in Michoacán and six in the State of Mexico. Five, covering 2.27 hectares, were inside the Monarch Butterfly Biosphere Reserve, and four, covering 0.66 hectares, were outside it. The largest, 1.62 hectares, was in the El Rosario ejido in Michoacán, inside the reserve. Bárcena put the smallest, at San Francisco, at 0.031 hectares.

CONANP put the increase down to more eggs and larvae during breeding in the United States, where spring and summer were less dry than in 2024, and to less drought along the migration, which left many flowering plants to give the butterflies nectar.

Against earlier seasons

Each figure comes from the CONANP release named in the table:

At 0.9 hectares, 2023-2024 was the second-smallest area since systematic monitoring began in 1993, CONANP said in February 2024; that season, the largest colonies were outside the reserve, in the State of Mexico. A CONANP release of 2022 quoted WWF Mexico's director putting 2018-2019 at 6.05 hectares.

The forest the colonies depend on

The reserve covers 56,259 hectares, with a core zone of 13,554 hectares where the main colonies settle, CONANP said in 2025. In its March 2026 release, CONANP put the forest affected in the core zone between February 2024 and February 2025 at 2.55 hectares, 32% less than the 3.728 hectares of the year before: 1.854 hectares by illegal logging, 0.579 by fire and 0.117 by drought. UNESCO recognized the core zone as a natural World Heritage property in 2008, CONANP has said, and the culture ministry's list still included the reserve on October 31, 2026.

Presenting the 2025-2026 figures, Bárcena named tourism, pesticides and climate change as three concerns, and announced the publication of the Plan de Acción para la Conservación de la Monarca 2025-2030.

Visiting the sanctuaries

In each of the last two seasons, CONANP announced the same four sanctuaries as open to the public, from 8 a.m. to 5 p.m.: El Rosario (Ocampo), Senguio (Senguio) and Sierra Chincua (Angangueo) in Michoacán, and Piedra Herrada (San Mateo Almomoloa) in the State of Mexico. It gave the opening periods as November 15, 2024, to March 31, 2025, and November 22, 2025, to March 31, 2026.

CONANP's press releases had not announced the dates of the 2026-2027 season by October 31, 2026, when this guide was researched. CONANP's code for responsible visitors in 2025-2026 asked people to:

• keep to the marked trails and follow the local guides;
• bring no food, alcohol, sharp objects, firearms or pets, and eat nothing inside the sanctuary;
• take no plants, animals or fungi, and never disturb, touch or take a butterfly;
• not smoke or light fires, use no flash, and use no hand sanitizer near the colonies;
• respect the viewing limits, stay quiet and stay no more than 18 minutes in the sanctuary, so that others can see the colonies without disturbing the hibernation;
• leave no litter or face masks.

What UK travel advice says

The UK Foreign, Commonwealth and Development Office (FCDO), in its Mexico travel advice last updated October 20, 2026, and still current on October 31, says: "FCDO advises against all but essential travel to the state of Michoacán, except the:"

• "city of Morelia accessed by federal toll roads 15D, 126 and 43; and the federal toll road 48D between the city of Morelia and the General Francisco Mujica airport"
• "town of Pátzcuaro accessed by federal toll roads 14D and 15 from Morelia, and boat trips out to islands on Lake Pátzcuaro"
• "federal highway 15D"

The three Michoacán sanctuaries open in the last two seasons are in Ocampo, Senguio and Angangueo, which are not named among those exceptions. On the State of Mexico, the FCDO says: "Criminal activity is a problem in the state of Mexico (‘Estado de México’). Take care when travelling through the state, as well as outside of tourist areas."