To avoid heat, July is all about high latitude and altitude, and I recommend visiting these northern mountain parks: Glacier, Lassen Volcanic, Mount Rainier, North Cascades and Rocky Mountain . While many other parks are hot and crowded, these are at their peak with plenty of space to explore.
The key to visiting Glacier is to understand that there is only one road through the park, and it doesn’t open until late June. The park is full of activities by June, but the accumulated snow takes a long time to melt at Logan Pass. And it’s a long way around. So if you want to see the sights and do the activities on both sides of the park, then you need to wait until July. August is even busier. The high mountain waterfalls are glorious along the Going to the Sun Road in July.
Lassen Volcanic similarly has its main road blocked late by snow, but by July almost everything is open including some wildflowers. For Bumpass Hell, the full trail usually opens later in July, but there are boiling mud pits and other fascinating volcanic features around the park. Fire damaged parts of the park have mostly reopened this year.
Mount Rainier too is better if you wait until July, when leftover snow recedes to open up roads and trails. I hiked the Paradise Trails in mid July and only crossed one patch of snow. Wildflowers were out, temps were pleasant and the mountain is big enough to handle many happy hikers. Plan your arrival, as the parking lots fill up.
North Cascades is also glorious in July, with wildflowers and waterfalls. Depending on where you want to hike, you may need to go later in the month for all roads to be fully open. But there are many great hiking options all month.
Rocky is another high elevation park, and July is a good time to see wildlife up there. I realize it’s crowded, but if you reserve campgrounds in advance you can reach the best areas early. Visiting in July means that you can move around early, like the elk, and it’s a good time to find bighorn sheep or pikas. I’ve visited in September and felt limited by wind and storms.
