Benito Juárez's climate is mild, with an average temperature of 15 °C (59 °F) and 1,030 millimetres (41 in) of precipitation annually.

Towards the Partido of Tandil is set the Tandilia System, an ancient mountain range and one of the oldest rock formations on Earth.

The most known hills are: "San Martín de la Tinta", "Lomadas" and "El Sombrerito".

The system is built on two billion year old igneous and metamorphic rock that most likely was a part of the supercontinent Rodinia when its coasts were uplifted during the Paleoproterozoic Era.

Many of these sediments consist of quartz arenite and claystones containing an abundance of fossils and offer insights into life on Earth after the Cambrian–Ordovician extinction event of 488 million years ago.