An interesting cloud pattern is seen over a carriage road on Day Mountain on Dec. 4, in Acadia National Park. Credit: Aislinn Sarnacki

BAR HARBOR, Maine — One of Maine’s signs of the annual “mud season” has arrived at Acadia National Park, where carriage roads are shut down to all users.

The National Park Service said the roads were closed on March 12 and will remain closed until they dry out and become firm enough to prevent damage to their gravel surface.

The historic carriage roads are a well-known feature at the national park. There are 45 miles of the roads, which the park service described as “the best and most extensive example of broken-stone roads in the United States.”

Mud season means inconveniences for walkers, cyclists and horseback riders throughout northern New England. Warmer weather and wet conditions have softened Acadia’s carriage roads, contributing to muddy conditions that exist in much of the state, the park service said.

The park service said hiking trails in Acadia are still open. Park Loop Road is closed to motor vehicle traffic until April 15.