Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
The observatories atop Mauna Kea, Hawaii, at 13,000+ feet. There was no snow at the time, but it was very cold. I don't handle elevation well and fell asleep on a couch, to be awakened by an "earthquake" --the observatory turning.
Mauna Kea, elevation 13,803 feet (4,207 meters). I had prepared for the cold, but it was surprisingly mild when I was there; didn't need a jacket or anything.
My next highest was the highest point on the Interstate Highway System: the Eisenhower Tunnel on I-70 in Colorado, at 11,158 feet (3,401 meters).
The peak of Mt Kilimanjaro - 5,895m (19,341 ft) 
Felt like I was dying too hahaha
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.