Flooding in Nuoro, north-east Sardinia. Photo: Vigili del Fuoco/Twitter

Sardinia is on extreme weather alert after storms dumped a quarter of the Italian island's average annual rainfall in the space of just two days.

The past 48 hours have seen roads closed, school suspended and rural residents left stranded as record rainfall flooded rivers and triggered landslides.

The Civil Protection Department issued a maximum red alert in three regions – Campidano di Oristano and Tirso near the central-west coast and Gallura in the north-east – until midnight on Thursday, while the rest of the island remains on orange alert. 

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Siniscola in the north-east saw 164 millimetres, compared to a monthly average of 36 mm and a yearly one of 666 mm. Nearby San Teodoro and Posada had 134 and 133 mm respectively, while the island's capital, Cagliari, had 68 mm of its annual 441 mm.

The storms are forecast to continue until at least Saturday. The island is also expecting winds of up to 100 kilometres an hour and strong waves around its coastline. Temperatures, meanwhile, have dropped some 20 degrees C from the early 30s of last weekend to around 12 midweek.

The bad weather will reach mainland Italy too: storms are predicted on Thursday and Friday in the north-west, especially Emilia-Romagna and Piedmont, as well as the central Adriatic coast and parts of the south. Parts of Abruzzo, Calabria and Sicily have issued orange alerts in anticipation of thunderstorms, high winds and even hail.