Snowpack levels are at their highest since 1999, causing some hikers to rework their plans.

Only five groups have attempted Mount Rainier’s scenic, 93-mile Wonderland Trail this year, and all have turned back because of snow.

Usually by late July, hundreds have made the loop around the mountain, said park ranger Daniel Keebler. This is also the time of year when park officials expect to see scads of day visitors on a mission to see wildflowers.

But after an unusually cold spring, late seasonal snow is putting a damper on such plans. Snowpack levels in the Cascades and Olympics are at their highest since 1999, according to data from the National Weather and Climate Center.

Visitors to Mount Rainier this weekend will find some trails still partially covered by snow, rangers say. But the seasonal snowmelt is under way. The Sunrise and Paradise areas at Mount Rainier are starting to clear up.

“Most of the day hikes have started to melt out,” said Casey Wilson, a backcountry ranger at Mount Rainier. But the melt is late. Data from June, the most recent available, showed snowpack levels at Paradise were 150 percent of average. Levels at the White River area, by Sunrise, were about 125 percent of normal.

Beyond their capabilities

Wilson talked with one of the Wonderland groups that turned back.

The hikers “said it was steep snow, and they basically decided it was beyond their capabilities,” he said.

Dan Hudson and Shanna Gerard live in Greenwater, just north of Mount Rainier. The couple are leaving on the Wonderland trail this weekend and plan to take it slow — 17 days. If they complete the loop in that time, they’ll be the first to do so this year.

“With all the experience we have, we’re not all that concerned,” Nelson said. “We’re prepared enough that we’re fairly confident.”

Mount Rainier has about 40 backcountry campsites and 14 of those have less than 50 percent snow cover, with the Carbon River area having the most snow-free sites, according to the park Web site. The Wonderland trail has 18 sites, and six are snow-free.

This season, the park has not seen many overnight campers, Wilson said, but he expects the numbers “are going to get to the normal levels pretty quick” as the snow continues to melt.

The snow has been an issue at Olympic National Park, too. All trails above 5,000 feet are covered. And in the Skykomish area of the Mount Baker-Snoqualmie National Forest, 35 of 40 trails are closed, park officials said.

Kelly Clayman, chair of the Seattle branch of the Mountaineers’ Hiking Committee, is not discouraged by the unusual snowpack. She takes large groups out on hikes around the region and says it’s been a record year for participation.

“We don’t cancel, we change our destination,” she said. “We just have to be careful that we pick hikes that are accessible.”

Wilson, the ranger at Mount Rainier, recommended people carry ski poles or ice axes on trails with snow. If hikers are not comfortable with those tools, they may want to avoid trails with a lot of snow.

“There are some instances of snow on almost all trails,” he said. “[But] until you get above 5,000 feet … you don’t really get that much.”

Unusually cool spring

The average temperature in the state this spring was 45.5 degrees, according to the office of the state climatologist, Phil Mote.

“There was an unusually cool spring, so [the snow] lingered,” Mote said. “It takes a long time to melt that amount of snow.”

Mote predicts the seasonal snowpack will have melted away completely by September.

Keebler said many hikers show up at Mount Rainier unprepared for the conditions and wind up going on easier hikes.

Meanwhile, conditions are better in the Enumclaw Ranger District, outside the northeaat corner of Mount Rainier park, where about 70 percent of trails can be hiked.

At Olympic National Park, spokeswoman Barb Maynes suggests people check the park Web site for conditions before deciding on a trail. Maynes said the east- and south-facing slopes are hikers’ best bets.

Jeff Raderstrong: 206-464-3301 or jraderstrong@seattletimes.com