One man has died and four people are missing following torrential rains that caused flash floods in northeastern Spain and disrupted road and air travel, officials said Wednesday.

The body of a man was found late on Tuesday in a beach in the town of Caldes d'Estrac some 40 kilometres north of Barcelona after he had been reported missing, regional police said on Twitter.

Emergency services said firefighters backed by a helicopter were looking for two people - reportedly a mother and her adult son - whose prefab home was swept away by floodwaters in Vilaverd, 30 kilometres from the port of Tarragona.

Rescuers were also looking for two people whose car was found in a river near the village of l'Espluga de Francoli in the same area.

Authorities said heavy overnight rainfall in the northeastern region of Catalonia caused power cuts that affected nearly 25,000 people while floods and landslides forced the closure of over 40 roads.

Spain's airport authority Aena said 37 flights were diverted, most had been due to land or take off from Palma on the holiday island of Mallorca.

Last month record rainfall in southeastern Spain claimed seven lives.

Last year 13 people died on Mallorca as intense rain caused rivers to overflow through streets and sweep away cars.