Deadly flash floods killed at least 12 people in the south of France at the weekend, while the remnants of Hurricane Leslie battered Portugal and Spain.
But new downpours are set to arrive in popular tourist areas including Marseilles, Barcelona and Malaga by the weekend, weather forecasters warn.
The Met Office said: “Further spells of severe #thunderstorms will affect many holiday spots across the western #Mediterranean through this week.
“Repeated torrential #rain could give up to 500 mm in places by the end of the week.”
The new alerts come after Leslie injured 27 people in Portugal on Saturday as it tore through the country with 60mph winds.
Authorities said at least 1,000 trees were uprooted, the majority of these in coastal towns north of Lisbon where the storm made landfall.
As the storm moved over Spain, trees were uprooted.
Flash flood warnings were issued for the north and northwest of Spain on Sunday.
12 people died in freak flash flooding on Mallorca less than a week ago.
The victims included British couple Antony and Delia Green, both in their 70s, whose taxi was swallowed by a raging torrent of water in the coastal area of Sant Llorenc.
In a statement issued by the Foreign Office, Mr and Mrs Green’s family said: “We are deeply shocked by the sudden passing of our parents Delia and Tony Green in the tragic events in Majorca.
“They were travelling out to Majorca for a two-week holiday when they were caught up in the flooding.”
The family also offered their condolences to the family of the taxi driver, Juan Sillero, who also died.
In the latest spate of wild weather, flash floods engulfed villages in south-west France after seven months’ of rain fell in a few hours.
A nun was swept to her death as floodwaters surged through the nunnery in the village of Villardonnel.
Resident Jean-Jacque Garros compared the damage to a “war zone”.
He said: “The village is more or less cut off from the outside world.”
France’s state meteorological service said the warm seas along the Mediterranean coast may be to blame for the heavy rains.
2018 is France’s warmest year since 1900, the country’s weather forecasting body said.