La Garrotxa is in the north of Catalonia, at the high basin of the river Fluvià, the Muga estuary, the river Brugent and the Llémena river bed.

In this county you can see two totally different types of countryside. In a large part of the southern half there are more than 40 volcanoes and various lava flows, forming a gentle countryside without dramatic gradients, which is protected by La Garrotxa Volcanic Zone Natural Park. From the Fluvià river valley to the county's northern limits, the landscape changes dramatically, becoming more dramatic and steeper with an abundance of cliffs and gorges. This is the Alta Garrotxa, which is a declared area of natural interest (Espai d'Interès Natural).

This whole area, along with others such as the river Fluvià, forms part of the Natura 2000 Network, a European initiative to protect the most unique, diverse, rare, well conserved, representative, fragile or vulnerable natural spaces and which share with each other similar characteristics.

The climate of La Garrotxa is medium mountain Mediterranean. Rainfall is abundant throughout the year, and the winter is the driest season. The frequent showers keep summers cool, while the influence of the Pyrenees makes the winters very cold.

The vegetation reflects the climate. While in the Alta Garrotxa and the east of the county there is an area of typically Mediterranean vegetation, the rest of the county is covered with sub-mediterranean vegetation that becomes Atlantic in the most humid parts. Holm oaks are typical on the sunny hillsides of the eastern sector, with relatively dry and hot summers, the oak tree predominates in other parts, and the beech is found in the most humid sectors.  On the Olot plain, the most characteristic natural species is the common oak, although nowadays its presence is limited to small woods found around the city.