Pisa Geography, Climate & Nature

Ten kilometres from a sea it used to sit on

Pisa straddles the Arno a short way before the river reaches the Ligurian Sea, on flat alluvial ground just four metres above sea level, across a municipality of 185 km². The city centre is now about 9.7 kilometres from the coast — and that number is the most important fact in Pisa's geography, because it used to be very much smaller.

The Arno carries silt, and for two thousand years it has been building land westward into the sea. Pisa was a working port and one of the Mediterranean's great maritime republics; the harbour that made that possible silted up, and the coastline has been retreating from the city ever since. The modern beach suburbs of Marina di Pisa and Tirrenia stand on ground the river deposited after the republic had already lost its sea.

The same silt explains the tower

Flat alluvial deposits are soft, waterlogged and unevenly compacted, and nothing heavy sits on them without moving. That is why the campanile in the Piazza del Duomo began to tilt before its third storey was finished, why the cathedral and the baptistery also lean very slightly, and why the square's buildings have needed monitoring for eight centuries. Pisa's most famous feature is a direct product of its geology.

A city of under 100,000 on a coastal plain

The municipality holds about 98,800 people at a density of 534 per km², which makes Pisa a small city carrying a very large reputation. The ground around it is flat in every direction: the Pisan plain runs north to the Serchio and south towards Livorno, bounded inland by the hills and seaward by pine forest and dune. Almost half of that coastal strip is now inside a regional park.

Between Mediterranean and subtropical

Pisa sits on the boundary between a humid subtropical climate and a Mediterranean one, which in practice means hot summers, mild damp winters and no reliably dry season. Annual precipitation is around 879 mm, and unusually for Italy it peaks in autumn rather than in winter or spring.

Proximity to the sea moderates the extremes. Records show a high of 39.5°C on 22 August 2011 and a low of −13.8°C on 12 January 1985, but both are exceptional; ordinary Pisan weather is milder than inland Tuscany in winter and slightly less fierce in summer.

Why this matters more here than elsewhere

Pisa's principal sight is an open square with almost no shade. That makes the weather a bigger planning factor than it would be in a city of museums and churches: a July afternoon on the grass of the Piazza del Duomo is genuinely punishing, and an autumn downpour has nowhere to shelter you. The city's answer in high summer is to open late — from 17 June to 31 August the monuments stay open until 22:30 — and taking that option is the single best weather decision a summer visitor can make.

Season by season

• Spring is the best: warm, long days, the square usable at either end of the day.
• Summer is hot and crowded together, with the evening opening as the compensation.
• Autumn is the wettest part of the year, but the crowd thins sharply from the second week of September.
• Winter is cool, damp and very quiet, with shorter monument hours.

What to pack for

Sun protection and water for summer, because the square offers neither. A waterproof for autumn. Layers in the shoulder months, when a bright morning and a damp evening are not the same temperature.

A Ramsar wetland on the city's doorstep

Pisa's natural interest is substantial, largely unvisited, and begins at the edge of the built-up area. The Parco naturale di Migliarino, San Rossore, Massaciuccoli, established by Tuscan regional law on 13 December 1979, protects more than 23,000 hectares of the coastal strip across the provinces of Pisa and Lucca, in the comuni of Pisa, Viareggio, San Giuliano Terme, Vecchiano and Massarosa.

Its significance is formal as well as scenic: 11,000 hectares of it — almost half the park — are designated a Ramsar wetland of international importance, which matters specifically for migratory birds. The Tyrrhenian coast is a flyway, and the park's lake, marsh and beach habitats are among the last substantial stopping places on this stretch of it.

What the park actually contains

• Lago di Massaciuccoli, the shallow coastal lake that is the wetland's core.
• The mouths of three rivers — the Serchio, the Arno and the Fiume Morto — each with its own estuarine habitat.
• San Rossore, a former presidential estate, now open and the most accessible part of the park from Pisa itself.
• The Tombolo, Migliarino and Macchia Lucchese forests, the coastal pine woods and dune systems that once ran along most of this coast.
• The Secche della Meloria marine protected area, managed by the same authority — the shoals off Livorno where the Pisan fleet was destroyed in 1284.

Why it survives

Much of this coast escaped development because it was a royal and then a presidential hunting estate rather than because anyone set out to conserve it — an accident of ownership that preserved dune and pine forest which has largely disappeared elsewhere on the Tyrrhenian coast. The park formalised in 1979 what private use had already protected.

Birds, and a flyway

The reason to think about wildlife in Pisa is migration. The Parco naturale di Migliarino, San Rossore, Massaciuccoli on the city's western edge holds 11,000 hectares of Ramsar-designated wetland, and the designation exists precisely because the lake, marshes and river mouths are an internationally important stopping point for migratory species on the Tyrrhenian flyway. Spring and autumn passage are what the site is for.

It is worth being straightforward that the sources used for this page establish that importance without naming individual species, so none is listed here. The park authority runs guided visits and publishes its own sightings, and that is the reliable route to knowing what is actually present in a given month — which for a migration site is the only question that matters.

The habitats, and what each is for

The Lago di Massaciuccoli is shallow open water and reedbed, the classic combination for waterfowl and marsh birds. The mouths of the Serchio, the Arno and the Fiume Morto add estuarine mud. The Tombolo and Migliarino pine forests and their dunes hold a different community again, and the Secche della Meloria marine area protects the shoals offshore.

San Rossore, and the deer

The former presidential estate at San Rossore is the part of the park most easily reached from Pisa, and the one where large mammals are genuinely likely rather than theoretical: the estate has been managed, fenced and hunted for centuries, which left it with grazing populations that open countryside nearby does not support.

A realistic expectation

This is not a reason to come to Pisa, but it is an unusually good reason to stay a second day. The park begins where the city stops, it is reachable without a car, and it is almost entirely absent from the itinerary of the millions who come for the square.