Mexican officials prepare for rain threat as Tropical Storm Sonia heads for Pacific coast.

MEXICO CITY – Officials on Mexico’s storm-struck Pacific coast braced Sunday night for the possibility of heavy rains with the arrival of fast-moving Tropical Storm Sonia, which was projected to hit the mainland by early Monday.

The U.S. National Hurricane Center said Sonia was centred about 115 miles (190 kilometres) south-southwest of Culicacan and 115 miles (185 kilometres) east of the tip of the Baja California late Sunday.

The storm had maximum sustained winds of 40 mph (65 kph), down some from earlier in the evening. It was heading north-northeast at 17 mph (28 kph).

Sonia could weaken some before coming ashore, and was likely to dissipate rapidly once over land, the centre said.

Ismael Checa Landeros, civil defence director for Sinaloa, the state in the storm’s path, said it was likely to hit near Culiacan, Navolato and Elota, all areas hit in September by Hurricane Manuel.

The government of Sinaloa state said school classes were cancelled for Monday in five municipalities that could be affected by the storm. Sixty shelters were being opened in case anyone had to evacuate their homes.

Checa said officials were on alert but had not yet decided if anyone would need to be evacuated.

In the resort town of Los Cabos in Baja California, officials opened a shelter for possible evacuees and said the port had been closed to small craft.

The U.S. hurricane centre said the storm could produce up to 6 inches (about 15 centimetres) of rainfall in Sinaloa and Durango states, with isolated areas getting as much as 10 inches (25 centimetres).