Residents and tourists in coastal states warned of intense rains at category three storm approaches Baja California Peninsula

Thousands of troops were put on alert on Saturday and businesses boarded up their windows as hurricane Blanca travelled toward Mexico’s Baja California Peninsula as a powerful category three storm.

The unpredictable Blanca, which strengthened suddenly from a category one to a category four storm on Saturday before weakening slightly, is expected to make landfall as a tropical storm on Monday. But authorities said its outer bands could start hitting the southern Baja California Peninsula as a hurricane on Sunday.

The director of Mexico’s National Water Commission, Roberto Ramirez, said he was concerned by Blanca’s “erratic” behaviour and warned residents along Mexico’s Pacific coast to be prepared for intense rains, including in coastal states of Guerrero, Michoacan, Colima and Jalisco.

In Baja California, 2,000 army troops and 1,321 marines have been put on alert, as well as emergency responders and power line technicians, said Civil Protection director Luis Felipe Puente.

He said there was a 70% hotel occupancy rate in Los Cabos and warned tourists to be attentive to any advisories issued by authorities.

On Saturday, some businesses and banks were seen hammering boards over their windows in preparation for Blanca’s arrival. People began lining up at gas stations to stock up on fuel.

Blanca’s maximum sustained winds on Saturday afternoon were near 120mph (195km/h), according to the US National Hurricane Center. The hurricane is centered about 320 miles (510km) south of Cabo San Lucas and is moving north-west about 10mph (17km/h).

A hurricane watch is in effect for an area from Cabo San Lucas to Santa Fe. A tropical storm warning is in effect from Loreto to Puerto San Andresito, including Cabo San Lucas.

Puente said he saw no reason to suspend local elections being held on Sunday.