MIAMI (AP) — Tropical Storm Colin formed along the South Carolina coast on Saturday, bringing the threat of rain and high winds for a day or two during the holiday weekend before improving for Monday's July Fourth celebrations.

The National Hurricane Center in Miami warned of the possibility of localized flash flooding along the Carolinas coast through Sunday morning. At 11 a.m. EDT Saturday, the storm’s center was about five miles (10 kilometers) west of Myrtle Beach, South Carolina, with maximum sustained winds of 40 mph (65 kph). It was moving northeast at 7 mph (11 kph).

The hurricane center said a tropical storm warning was in effect for a stretch from north of Little River, South Carolina, to Duck, North Carolina, including Pamlico Sound. The storm is not expected to strengthen as it moves into the Atlantic on Monday.

“Colin will continue to produce locally heavy rainfall across portions of coastal South and North Carolina through Sunday morning,” the center said. Isolated amounts could reach up to 4 inches (10 centimeters).

“This rainfall may result in localized areas of flash flooding,” the center said.

Some Fourth of July celebrations planned Saturday in Charleston, South Carolina, were canceled after significant water had pooled on the field at Joseph P. Riley Jr. Park and more rain was expected.

“Obviously, we’re disappointed,” said Scott Watson, the city's director of cultural affairs. “This promised to be a great family event, and we hate to have to cancel.

Organizers were also forced to cancel a festival planned in Southport, North Carolina.

“The safety of Festival goers, vendors, volunteers, emergency workers and everyone is our highest priority,” festival spokesperson Trisha Howarth said in a statement.

Separately, the center of Tropical Storm Bonnie rolled into the Pacific on Saturday after a rapid march across Central America, where it caused flooding, downed trees and forced hundreds to evacuate in Nicaragua and Costa Rica. There were no immediate reports of deaths.

Late Saturday morning, the storm was centered about 65 miles (100 kilometers) south of the Nicaraguan capital, Managua, with maximum sustained winds of 40 mph (65 kph). It was moving to the west at 15 mph (24 kph).

It’s one of the rare storms to make an Atlantic to Pacific crossing without losing tropical storm force, thus maintaining its name. Forecasters said Bonnie is likely to become a hurricane this week off the southern coast of Mexico, but was unlikely to make a direct hit on land.

Many Nicaraguans still remember Hurricane Joan, a powerful 1988 storm that wreaked havoc on the coast and caused almost 150 deaths in the country.

“We are waiting for the storm to hit, hoping that it won't destroy our region," Bluefields resident Ricardo Gómez, who was 8 when Joan hit, said before Bonnie arrived.

The area was also battered by two powerful hurricanes, Eta and Iota, in quick succession in 2020, causing an estimated $700 million in damage.

Officials in Costa Rica expressed concern that the storm would unleash landslides and flooding in an area already saturated by days of rain. The government said seven shelters in the northern part of the country already held nearly 700 people displaced by flooding.