The sky gives plenty of warning if you know what to watch. A field guide to spotting trouble before it arrives.
Forecasts are better than they have ever been, but mountains make their own weather, and the gap between the valley forecast and the summit reality can be enormous. The hiker who can read the sky directly holds a decisive advantage, because the mountains almost always warn you before they turn on you.
Clouds are the clearest language. High, wispy streaks thickening and lowering through the day often mean a front is approaching, with rain a day or so out. Small puffy clouds that build vertically through a warm afternoon, towering into anvils, signal thunderstorms brewing — a cue to be off exposed ridges and summits well before they mature.
Wind and pressure speak too. A steady drop in pressure, a wind that swings direction and strengthens, a sudden clammy stillness after hours of breeze — each is a hint that the air is reorganizing itself, usually not in your favor. None of these is a certainty on its own, but stacked together they tell a story worth heeding.
The real skill is not prediction but response. You cannot control the weather, only your exposure to it, so the mountain wisdom is to make decisions early, while you still have options. Turning back with the sky merely looking wrong, rather than waiting for certainty, is the mark of someone who intends to keep doing this for a very long time.
Replace this with your own take: the sky signal you always watch for, the day the weather changed faster than forecast, and the turnaround decision you were glad you made. — Written by the editors.