June 30, 2025 – The mountains are calling and we must go... slowly, because we’re out of breath! 

As the high-country thaws out, the highest points of the park are becoming reachable. At increasing elevations, the partial pressure of atmospheric gases decreases. Put simply, this means the atmosphere is thinner than it is closer to sea level. Spending time up in these high elevations can be magical but come prepared for a different environment.

As the partial pressure of atmospheric molecules drops, so do temperatures. In practical terms, expect significantly cooler temperatures around areas like Tioga Road, where the elevation reaches 9,945 feet above sea level (and even higher depending on where you hike.)

A thinner atmosphere absorbs fewer UV rays, meaning sunburn can happen faster. Use sunscreen or wear protective layers and remember that sunburn can happen even with clouds overhead.

Speaking of weather, storms can develop quickly and unexpectedly. Afternoon thunderstorms are common at high elevations in the warmer months. Getting caught in a lightning storm above the treeline is especially dangerous. Brush up on lightning safety before going out for a hike in the high country.

We weren't kidding about being out of breath, hikes at elevation are liable to take longer than you expect and feel harder. Have patience for yourself and others. In some cases, being at high elevations can cause acute mountain sickness. Watch for symptoms which can include nausea, headaches, and dizziness, and modify your activity or seek medical help as necessary.

Source & photo: NPS