It has been raining so much that the river Tiber has reached alert levels. When the water exceeds the containing walls, substantial areas of the city become vulnerable to the river's occasional transgressions. Last year around the holiday season, Rome feared the Tiber would burst its banks after days of rain and thunderstorms. The mayor declared a state of emergency after severe storms flooded underpasses, disrupted train and flight services and killed one person. Hopefully this year this won't happen.