Like clockwork, the rain fell right on schedule. Gathering stormclouds had shaken off occasional droplets over the last three hours, but by 4:00 the thunderheads had reached full strength, and the teasing was over. With a furious, deafening boom that reverberated across the San Juan Mountains, the storm unleashed a torrent of rain upon the grasses and stones of the alpine tundra. Fortunately for me, by then I was sitting comfortably in my tent below treeline, reading a tattered, secondhand book of old ghost stories. For all their thunderous boasting and bluster, Colorado’s summer thunderstorms are shamefully predictable, if you pay attention to the signs.

I had chosen to temporarily give up the luxuries of car camping in order to backpack deep into the San Juans on a four-day adventure. I’d attempted the route last summer but had to cut my journey short due to an overabundance of snow. It was beautiful country, with mountains the color of iron and rust, and golden eagles circling overhead. But I was also sick, with a bad head cold, and I built a campfire that first night under the shelter of tall spruce trees to help me stay warm and dry. I had no chicken soup, but I did have chicken-flavored ramen noodles, which was the next best thing. And when the sun set that evening, it passed through the narrow space between the dark cloudmass and the horizon, creating a stunning complete rainbow against the backdrop of pink-hued stormclouds. For all my knowledge of Colorado weather, the sight was something I completely failed to predict.

To avoid the afternoon thunderstorms, I was forced to break camp early each morning, despite my body’s desire for greater rest. On the second day, I noticed a higher-elevation trail on my topo map that promised more far-reaching views than the valley-bound course my guidebook recommended. Unsure of how I would reconnect with my planned route later on, I nonetheless succumbed to temptation and struck off up the faint trail once I encountered it.

Encountered is perhaps the wrong word. The trail and I developed only a passing familiarity with each other, for over the course of three miles it vanished often and only put in the occasional guest appearance. It was about now that I noticed my map hadn’t been edited since 1955. Hmmmm… Sometime in the last fifty years the route had fallen into disuse, and apparently the tundra around here rebounds from human impact much faster than the hundred-year timetable for recovery I’d always heard. At least I could read the contours on the topo map and tell from the elevation of the land where the trail was supposed to be. As long as I didn’t get lost outside the boundaries of the map, I was okay.

I saw no one as I traversed the lonely alpine terraces, yet I was not afraid, for my sneezes would have scared away bears, mountain lions, or anything else within a five-mile radius. Eventually I found myself at the place on the map where the disused trail dead-ended, at the bottom of a gully leading up to a saddle between two 13,000-foot summits called the Twin Sisters. Stormclouds were coalescing, but I knew I had enough time to climb both mountains before lightning became a severe danger.

So I ditched my backpack and began to scramble up the steep slope of purple and green scree. It was tough terrain. The mountains in the San Juans tend to be rather fragmented, making for loose footing and unreliable handholds. In addition, I was feeling a headache, mild dizziness and nausea – the classic symptoms of altitude sickness. After too many weeks at sea level, I had yet to fully acclimatize to the low oxygen levels at these elevations. The energy I should have been using to make more red blood cells to transport oxygen more efficiently were being used instead to make white blood cells to fight off my current viral infection. Yet, I gained both summits in time and surveyed the scene.