They were last seen at approximately 10:15 a.m. Sunday, setting off from Abol Campground towards the summit, Baxter State Park officials said.

Trail guides and experts have some pointers on how to prepare to climb Katahdin.

“People underestimate how challenging it is,” said Jesika Lucarelli, a Registered Maine Guide who’s been leading hikes up Katahdin since 2012. “People often look at a route and see it’s only 4.5 miles to the summit, but they don’t understand how rugged the terrain is.”

Mount Katahdin rises sharply from the northern wilderness. The trails scramble over steep, often slippery rock with limited visibility. “That’s why we say climb Katahdin and not hike it,” said Lucarelli.

Round-trip hikes average 8–12 hours, and all Katahdin trails are rated “moderate” to “extremely strenuous,” according to the Baxter State Park website.

The weather can change fast, especially in the “shoulder seasons” of late spring and early fall.

“The mountain is so high, it creates its own weather patterns,” said Tori Gray, a Registered Maine Guide and former Baxter State Park ranger. “Thunderstorms can roll in that weren’t even on the weather forecast. It happens very quickly, in a matter of minutes.”

Because conditions can change quickly, Noah Kleiner, a certified guide who leads hikes in summer and winter said he’s “always collecting data,” paying attention to both the environment and how his body is responding “in order to make the right decision.”

“It’s really rugged, it’s true wilderness, and sometimes that’s lost on people,” Gray said.

“Wilderness first, recreation second” is a guiding principle at Baxter State Park, Gray said. “The park promotes and stands by a primitive experience,” she said.

The most important thing is knowing when to turn around. Gray said. “A lot of hikers are super experienced, but they have summit fever, they don’t care about anything but reaching the summit,” she said.

“But in a situation where you’re not feeling safe or comfortable on the mountain, say you see dark clouds or your ankle is starting to bother you, turn around.”

“The hike doesn’t end at the summit,” she said. “It ends in your car.”

“The mountain will always be there, it’s not going anywhere, whether I get to the summit today or tomorrow,” Kleiner said. ” And I think people forget that when they’re there. But you have to ask, what is the risk? And is it worth more than [reaching] the summit?”

Rita Chandler can be reached at rita.chandler@globe.com.

The body of a missing woman was found on Maine’s Katahdin mountain Wednesday, a day after her father’s was found, officials said.

Esther Keiderling’s body was found about 1 p.m. off the wooded area known as Tablelands, a Maine Warden Service representative told NBC affiliate News Center Maine.

The discovery ended a dayslong search — the father and daughter from New York’s Hudson Valley were last seen Sunday.

The body of her father, Tim Keiderling, was found about 2:45 p.m. Tuesday. on the Tableland, near the summit of Katahdin, Maine’s highest mountain, officials said.

Tim, 58, and Esther, 28, were last seen at a campground Sunday morning on their way to the summit of Katahdin, Maine’s tallest mountain, according to a post on the Baxter State Park Facebook page.

Park rangers began searching for the Keiderlings on Monday morning, when their vehicle was spotted in day-use parking, searching trails near the Abol Campground, where they’d been, without finding any sign of them, according to the post.

Several helicopters and more than 30 game wardens joined the search on Tuesday, finding no trace of the pair as of about noon on Tuesday, park rangers said.

The Keiderlings are from Ulster Park, a town on the Hudson River near Kingston.

Ground-level ozone concentrations are expected to reach the ‘Unhealthy for Sensitive Groups’ (USG) level according to Air Quality Meteorologists at the Maine Department of Environmental Protection. 

Ozone is expected to reach USG levels along the coast from Kittery through Acadia National Park on both Wednesday and Thursday, according to the Maine Dept. of Environmental Protection.

The Downeast Coastal, Western Interior, and Eastern Interior regions are expected to reach Moderate levels. Ozone has been building over the Mid-Atlantic region on Tuesday, with this airmass projected to move over Southern New England and into Maine on Wednesday. Meanwhile, Particle Pollution is expected to be Moderate statewide on Wednesday due to wildfire smoke entering the region.

On Thursday, weather conditions are expected to remain consistent, and currently, Air Quality Forecasters are not expecting pollutants to move out of the Maine area. USG levels of ozone are expected for the Southwest and Mid-Coastal regions with the Downeast Coast, Western Interior, and Eastern Interior remaining Moderate.

For particle pollution, the entire state of Maine is expected to remain in the Moderate range since smoke can be slow to clean out. However, please check the website Thursday morning for the finalized forecast.

At elevated ozone levels, children, the elderly and individuals suffering from respiratory or heart diseases such as asthma, bronchitis or COPD can experience reduced lung function and irritation.  In addition, healthy adults who exert themselves outdoors may also notice these health effects.  Affected individuals may notice symptoms such as coughing, shortness of breath, throat irritation and/or experience mild chest pain.

Some actions you can take to protect your health during such periods of include:

• Avoiding strenuous outdoor activity
• Closing windows and circulating indoor air with a fan or air conditioner
• Asthmatics should keep their quick-relief medications and action plan handy

Additional health information may be found on the following websites:

In addition to those in a sensitive group, others who are responsible for the welfare of people impacted by poor air quality are urged to use one of the listed tools to follow the Air Quality Forecast:

For more information go to Maine DEP’s air quality web site www.maine.gov/dep/air/aqforecast.