With an elliptical shape, Terceira Island has an area of 403.4 km2 and reaches its highest point at 1021 metres in the Serra de Santa Bárbara.
With 29 kilometres long towards east-west and 17.5 kilometres of maximum width, its latitude and longitude are of 38° 43’ 00’’ N and 27° 12’ 00’’ W.
The island has two counties, Angra do Heroísmo and Praia da Vitória, is divided into 30 parishes and has a resident population of about 56 500 inhabitants, being the second most populous in the region.
It has a temperate maritime climate, with a low-temperature range and high relative humidity. Monthly average temperatures range between 14 °C in February and 24 °C in July and August.