Civil protection authorities in Rome have declared a state of alert ahead of a storm predicted on Monday 15 October.

Some of the districts most at risk are identified as Prima Porta, Fiumicino, Tiburtina and Piana del Sole, while 20,000 sandbags were placed along the Canale Palocco in Ostia.

Hundreds of workers and volunteers are busy freeing up the capital's drains before the heaviest rains – predicted for after 20.00 – and the city has made 500 places available for Rome's homeless people, in the area around the ex-Fiera di Roma on Via Cristoforo Colombo.

The superintendent for cultural heritage Umberto Broccoli said his department has put measures in place to help ensure the safety of Rome's most fragile heritage sites, such as Trajan's Markets.

However the mayor Gianni Alemanno said that the storm had been "downsized" and defended his decision not to close the city's schools.