A hurricane packing a punch rarely witnessed in the mid-Atlantic Ocean is bearing down on the Azores, placing emergency services on red alert for waves that could reach eight storeys high, winds that could flatten homes and heavy rain that could turn into torrents on steep mountains.

Category 2 Hurricane Lorenzo is expected to hit the Portuguese islands on Tuesday night and Wednesday morning. Waves up to 72ft high and hurricane wind gusts over 124mph are forecast for some islands.

The US National Hurricane Centre in Miami issued hurricane warnings for seven of the Azores’ nine volcanic islands and a tropical storm warning for the other two.

The remote islands are home to about 250,000 people.

Lorenzo was previously a Category 5 hurricane, the strongest storm observed so far north and east in the Atlantic basin. It is already producing huge seas over the North Atlantic, according to the hurricane centre.

Severe weather conditions are not uncommon in the exposed island chain, but hurricanes have usually eased by the time they reach the area’s cooler waters.

Nuno Moreira, head of the weather department at Portugal’s Institute for the Sea and Atmosphere, said Lorenzo is so big it is taking longer than usual to weaken.

“It’s a rare event … but not unique,” Mr Moreira said, noting that two storms of similar strength hit the islands in the 1990s.

Scientific studies have indicated the Azores should expect more powerful cyclones in the future due to climate change, Mr Moreira said, as the atmosphere and oceans heat up.

The centre of Lorenzo is expected to pass near the western Azores early on Wednesday.

The Azores regional government sent crews out to clear drainage systems during calm daytime weather on Tuesday and told residents to prepare their homes.

It also cancelled Wednesday classes at schools and told government workers to stay at home, except for emergency workers.