10 of the best national parks to visit in the summer, and 2 to avoid, according to a couple who have been to all 63

If you're considering stopping by Death Valley this summer, the Smiths would highly encourage otherwise.

As much as they love the Californian desert park, hiking the Gower Gulch Loop, and soaking in the sunset views from the Mesquite Flat Sand Dunes, Matt and Karen said the sweltering heat conditions in the summer aren't worth the hassle.

"We love Death Valley," Matt said. "Don't go to Death Valley in the summer. It's not because Death Valley is a bad park. It's that the heat can kill you, literally."

He has a point. In early July 2023, tourists made headlines for arriving at the park in droves despite the NPS issuing multiple warnings of a dangerous heat wave reaching temperatures of 130 degrees Fahrenheit. Several deaths were reported in the aftermath, including that of an older hiker, who the NPS reported was discovered collapsed by a restroom near the Golden Canyon trailhead.

For a safer, less brutally hot visit, the Smiths recommend planning a trip in January or February.

In the same vein, Matt and Karen would advise against visiting Joshua Tree National Park in the summer as it can get "brutally hot."

Instead, they say the best time to go is January and February when temperatures are cooler.

When you arrive, they suggest trekking their favorite hike, the Panorama Loop, which they say is less crowded and offers great views.

According to Karen, some of the best national parks to visit in the summer are high alpine parks "in the general northwest part of the country."

The Smiths say North Cascades is a prime example and provides a perfect visit from July to September.

The alpine hiking trails are reminiscent of the Swiss Alps and make you feel like you're in the wilderness despite only being a few hours from busy cities and towns like Bellingham and Mount Vernon, they added.

Mount Rainier is only a few hours from the Smiths home in Washington, which is convenient since it's one of their favorite parks to visit in the summer.

"Mount Rainier isn't quite as popular as some of the others, but Mount Rainier is incredible," Karen said. "It's like you're in Switzerland. It's world-class hiking at Mount Rainier."

One of their favorite spots in the park is the Sunrise area, which they say is accessible by car from July 1. "Mount Rainier is literally in your face," Karen added.

In Montana lies Glacier National Park, which the Smiths say offers hiking experiences in areas like Logan Pass or Many Glacier that rival the Swiss Alps.

Besides the hiking, the couple says the best reason to visit Glacier is for the panoramic views you get while driving down the Going-to-the-Sun road.

The only caveat the Smiths have is that the window of time to visit Glacier in the summer is slightly tighter. They'd recommend visiting from mid-July to mid-September, though, toward the end of that period, they warn that weather can turn from full-on summer to winter storms in just a few days.

Another national park that the Smiths recommend visiting in the summer is Crater Lake in Oregon. One of the reasons is that many of the roads in the park "don't open until at least July 1," Karen said.

But, more importantly, the couple say views along the rim of the crater are the most spectacular and unobstructed by clouds during the summer, from July to September.

Yosemite is "a beauty" and "a great one to visit" from July to September, Matt says.

It's not impossible to visit in the winter, he added, but it's not the same since most of the high-elevation areas and roads are closed off.

As Yosemite is one of the most popular national parks, the couple likes to avoid crowds by opting for less popular high-country trails in the Tioga Pass area, which they say are just as good as the more well known trails.

For those interested in escaping the crowds at a national park in the summer, the Smiths would encourage looking into Kings Canyon in California.

The Cedar Grove area of the park is similar to Yosemite Valley, but without the crowds, they say. While access depends on the snow conditions, they say the best chances of a successful visit is from July to September.

As the name suggests, the towering Sequoia trees are the main draw of visiting this national park, the Smiths said.

However, they say it's also home to some great hiking, through areas like the Giant Forest and trails leading to the top of Moro Rock.

Given the park's high elevation, Sequoia gets quite a bit of snow. According to the couple, it's best to go in the summer when temperatures are warmer and the snow has melted. That said, hiking in the winter when the roads are cleared can be a magical experience.

The Smiths' favorite activities in Yellowstone are hiking to the overlook of the Grand Prismatic Spring and driving through the Lamar Valley to see bison roaming.

From late spring to mid-June, the couple say visitors also have the opportunity to see a lot of baby bison, nicknamed "Red Dogs" for the orange tint of their fur after they're born.

It's important to remember that it can snow in Yellowstone no matter the time of year. However, Matt and Karen say it's generally not an issue from Memorial Day to Labor Day.

"Grand Teton is another phenomenal park that you should visit in the summer," Karen said, specifically between Memorial Day to Labor Day.

Located less than a three-hour drive from Yellowstone, the park is home to a bounty of wildlife, including grizzly bears, so the couple encourages visitors to carry bear spray with them.

Being the avid hikers they are, the couple recommends hiking to the west side of Jenny Lake and into Cascade Canyon, where they say they regularly spot moose.

"If people want to see the Alaska parks, you want to go in the summer," Karen said.

While some of the Alaska parks are pretty remote and less accessible, like Wrangell St. Elias, one of the most convenient to visit is Denali.

"It's just a couple of hours north of Anchorage," Karen said. "So it's one of the easiest parks to get to and it's also phenomenal."

The couple said that with a permit, visitors can ride a bus into the park and enjoy the vast wilderness it offers.

Matt and Karen added that the best time to go is in August because it's less cloudy, so there's a higher chance of getting a clear view of the mountain, and, importantly, because there are mosquitos.