Tropical Storm Alma, the first cyclone of the Americas hurricane season, slammed into Nicaragua's Pacific coast on Thursday, killing one person as winds toppled trees and ripped roofs off flimsy homes.

Torrential rain fell in this colonial western city as Alma whipped up sustained winds near 65 mph (100 kph) and even higher gusts.

The former capital of Nicaragua - home to around 150,000 people - was without electricity and telephone services, and shantytowns were flooded, witnesses said.

Troops in military vehicles dashed out to towns along the coast to evacuate people in danger by the busload. But other residents, many of them survivors of previous storms, were reluctant to leave their homes.

One man was killed in the coastal fishing village of Masachapa when he was electrocuted by downed power lines, said the head of the national defence forces.

"Shelters are ready but some people are waiting a bit to evacuate," Lt. Col. Gilberto Narvaez told Reuters.

Hurricane Mitch devastated Central America in 1998, killing 10,000 people.

But Alma hit land before it could gather enough strength to become a hurricane.

Nicaraguan authorities had planned a mass evacuation on the Pacific coast of the poor Central American country, where they said 25,000 people were at risk.

In neighbouring Honduras, the government ordered the evacuation of up to 4,000 people from low-lying coastal areas under threat from expected sea surges and flooding.

Up to 55,000 other Hondurans have been instructed to abandon their homes if rivers break their banks or if there are mudslides, emergency commissioner Francisco Moncado told Reuters.

Alma made landfall over Nicaragua on Thursday afternoon and was due to head further inland toward eastern Guatemala, according to the Miami-based National Hurricane Center.

Heavy rains could hit Central American coffee growing areas if it continues on its current path.

"Isolated maximum storm total amounts of rain of 20 inches (51 cm) are possible in areas of high terrain. These rains may produce life-threatening flash floods and mudslides," the center said in a statement.

There are no oil platforms or other major energy interests along Alma's expected path.

The eastern Pacific hurricane season began on May 15.

The energy, commodities and insurance markets are usually more concerned with the Atlantic hurricane season, which starts on Sunday. It is Atlantic storms that routinely threaten heavily populated U.S. shores, cotton and orange crops and energy rigs in the Gulf of Mexico.