Risk on a hike is not bad luck. It is the product of exposure, likelihood and consequence — and you control all three by choosing where to go, when to go, and what gear you carry. A sunny day on a forest path is low risk; a sudden storm on an exposed alpine ridge is a different world. This guide teaches you to read forecasts, recognize dangerous terrain, and apply a simple go/no-go test before every trip.

1. Reading the forecast: the four numbers that matter

Do not just glance at the temperature. Look at four things:

• Wind: wind chill strips heat fast. A 40 km/h wind at 10°C feels near freezing on an exposed ridge. Strong wind also makes exposed scrambling dangerous.
• Precipitation: look at timing and amount, not just a percent. Rain on rocks means slippery; rain overnight means swollen streams in the morning.
• Thunderstorms: the single biggest weather killer on trails. If thunder is forecast for the afternoon, you must be off the exposed high ground by midday.
• Temperature swing: mountain air can swing 15–20°C between morning and afternoon, and another drop once the sun goes. Plan layers, not one outfit.

2. Mountain weather behaves differently

Valley forecasts lie about the high country. Temperature drops roughly 6.5°C for every 1,000 m of elevation gain, so the summit is far colder than the valley. Clouds form on peaks in the afternoon and can roll in fast, wiping out visibility. Wind funnels through gaps and ridgelines far stronger than the valley reading suggests. Always forecast for your altitude, not the trailhead.

3. Recognizing dangerous terrain

Terrain risk multiplies weather risk. Learn to flag these features on the map:

4. The go / no-go decision tree

Run through these questions the night before. If any answer is a hard "no", reconsider the trip:

1. Is lightning forecast on exposed ground we plan to be on? → No-go on the ridge; choose a forested route instead.
2. Is wind strong enough to threaten the exposed sections? → Turn back early or pick lower ground.
3. Do we have the gear for the worst-case forecast temperature? → No shell or warm layers? Do not go.
4. Can we finish the planned route two hours before the worst weather? → If not, shorten the day.
5. Does everyone in the group know the bailout and turnaround point? → If not, fix that before leaving.

5. When the weather turns on the trail

If a storm surprises you: get off exposed ridgelines immediately and avoid tall isolated trees; do not stand under the highest point. Put on every layer before you are cold — once shivering starts, it is hard to reverse. If visibility drops, stop and navigate carefully rather than guessing your way off the hill. Conserve energy, stay with the group, and wait it out in a sheltered spot if needed. A calm hour in the trees beats a panicked descent in whiteout conditions.

6. Know the signs of heat and cold illness

Weather risk becomes medical risk fast. Watch for hypothermia even in mild temperatures: uncontrollable shivering, slurred or slow speech, confusion, and clumsy hands are early signs. Get the person sheltered, add dry layers, and give warm sweet drinks. In the other direction, heat exhaustion shows up as heavy sweating, dizziness, nausea and a rapid pulse — stop in shade, remove layers, and cool and rehydrate. Both conditions worsen quickly when you are tired, wet and alone. If someone stops making sense, treat it as an emergency and call for help.

Use more than one forecast source and look at the hour-by-hour outlook for your exact elevation rather than the nearest town. Mountain forecasts update fast, so check again the morning you leave, not just the night before. A 24-hour-old forecast on a ridge is a guess.

Share your plan with someone off the mountain, and set a turn-around time as non-negotiable as your gear. Most emergencies do not happen to unprepared people alone — they happen to prepared people who chose to push on when the evidence said otherwise. Respect the signals, and the mountains will keep you around to visit them again.