As the muggy heat eases but the days remain bright, a warm outdoor soak feels particularly welcome. Italy has free thermal springs, natural pools and waterfalls where access is free all year round.
September makes the experience even better, with fewer people than during peak season and temperatures that make it easy to stay in the water for a while. Here are four well-known spots, along with a few useful details for planning the day.
Cascate del Mulino (Saturnia), Maremma
The Cascate del Mulino are the best-known symbol of Italy’s free thermal baths. The Gorello stream runs through natural travertine pools arranged over several levels and fed by water rising from the Saturnia spring.
Access is free year-round, and no booking is needed, which makes it a tempting stop even for a short off-season break.
In September, spending time in the water is more comfortable than during the summer months, with the pools staying at around 35–37°C. Its popularity means it can get busy, especially at weekends. Things tend to be quieter at sunrise or later in the afternoon.
Bagni San Filippo (Fosso Bianco), Val d’Orcia
At the foot of Monte Amiata, thermal springs feed the Fosso Bianco, creating warm pools and small waterfalls in the heart of the woods. The scenery is shaped by almost white limestone deposits, including the celebrated Balena Bianca, or White Whale formation, gradually moulded by flowing water over time.
Access is via the pedestrian entrance off Via San Filippo, followed by a walk along a path surrounded by vegetation. The area is open and free of charge.
September creates an appealing balance: outdoor temperatures begin to drop, but the woods still retain their summer greenery, adding to the feeling of being in a quiet oasis. The ground around the stream is often damp, and the mineral formations are delicate, so careful and respectful movement is needed.
Petriolo free thermal baths (Farma River)
Along the border between the areas of Monticiano and Civitella Paganico, thermal water rises at around 43°C and flows towards the Farma River, forming open-air limestone pools. Hot water meets the river water, creating a mix of temperatures that feels especially pleasant in September.
The free section sits beside the remains of the old thermal structures and is separate from the equipped spa, where access to therapeutic pools is paid. The natural pools continue to be promoted by the regional tourism board as free thermal baths.
For those who prefer facilities and changing rooms, the Terme di Petriolo spa reopened on 1 September 2026 after its summer break. Entry to the thermal pools costs €15 and does not require booking.
Piscine Carletti and Bullicame (Viterbo)
Several natural thermal areas lie just outside Viterbo. Piscine Carletti, around 2.5 km from the town centre, is a free area with open-air pools supplied by water that reaches roughly 58°C at the source. There is no night-time lighting or the usual spa facilities, so daytime visits work best and it is worth bringing everything needed for the stop.
Not far away is the Bullicame, one of the city’s historic springs, mentioned by Dante. The water emerges at around 58°C, and the freely accessible park has two pools fed by the spring.
A visit can be combined with time in Viterbo’s historic centre, particularly the medieval San Pellegrino quarter.
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