MEXICO CITY -- About 1,400 people sought refuge at storm shelters in the Los Cabos resorts at the tip of the Baja California Peninsula on Thursday as a strengthening Tropical Storm Lidia closed in on an area just to the north.

Lidia spread rains over a broad swath of Mexico, including Mexico City, where it was blamed for flooding that briefly closed the city's airport. An enormous sinkhole about 30 feet (10 metres) in diameter opened on a street in downtown Mexico City because of an accumulation of water.

Civil Defence Commissioner Luis Felipe Puente said strong winds and rain were already lashing Los Cabos at midday. Authorities also warned residents to prepare for a possible dangerous storm surge.

The U.S. National Hurricane Center said Lidia could produce total accumulations of as much as 8 to 12 inches (20 to 30 centimetres) across much of Baja California Sur state and western Jalisco state on the mainland, threatening flash floods and landslides.

Lidia had maximum sustained winds of 65 mph (100 kph) at midafternoon and some further strengthening was possible before landfall later Thursday. Its centre was about 40 miles (70 kilometres) northwest of Cabo San Lucas and heading north-northwest at 10 mph (17 kph).

The storm was predicted to move northward about half way up the peninsula over the next two day before turning out into the Pacific.

Far out over the Atlantic, meanwhile, Hurricane Irma formed and strengthened to a category 3 storm while following a course that could bring it near the eastern Caribbean Sea by early next week. Its maximum sustained winds had increased to near 115 mph (185 kph).

Irma was moving west-northwest near 12 mph (19 kph) and that general motion was forecast to continue through early Friday.

Forecasters said Irma was expected to be an extremely dangerous hurricane for the next several days. No coastal watches or warnings were in effect.