Mountain thunderstorms follow a daily rhythm in many ranges: clear mornings, building cloud by midday, storms in the afternoon. The most effective lightning safety measure is scheduling rather than technique — be off exposed terrain before the storms arrive.
- 1
Plan around the pattern, not around the forecast
In many mountain areas, an alpine start and being off summits and ridges by early afternoon removes most of your exposure. This single habit does more than every other precaution combined, because the alternative is making decisions while a storm is already on you.
- 2
Read the building signs
Cumulus clouds growing vertically through late morning, darkening bases, a sudden drop in temperature, gusty wind shifts, and the smell of rain. A barometric altimeter showing a falling trend over a few hours gives useful warning before the sky looks threatening.
ABC watches explainedUsing barometric trend as an early signalRead Guide → - 3
Use the flash-to-bang count
Count seconds between the flash and the thunder and divide by five for distance in miles. Thirty seconds means roughly six miles, which is close enough to take shelter. A widely used guideline is to wait 30 minutes after the last thunder before resuming exposed travel.
- 4
Get off the terrain that attracts strikes
Descend from summits, ridges, and exposed saddles. Avoid isolated tall trees, open meadows where you are the high point, cave mouths and overhangs, and anything metal including fences and via ferrata cable. Water is particularly hazardous — get off lakes and out of the water immediately.
- 5
If caught in the open, minimise exposure
Move to lower ground and into uniform lower vegetation rather than isolated tall trees. Spread the group out so a single strike cannot injure everyone. Crouch low on the balls of your feet with feet together to reduce ground current path, rather than lying flat. Put a pack or pad underneath you if available.
- 6
Know that any strike injury needs medical help
Anyone struck by lightning needs emergency medical care regardless of how well they seem — injuries can be delayed and internal. People struck carry no electrical charge and are safe to help immediately. Where there is no phone signal, a satellite communicator is how you call for that help.
Using SOSCalling for emergency help without coverageRead Guide →
Terrain Risk
| Avoid | Prefer |
|---|---|
| Summits and ridgelines | Lower ground, below treeline |
| Isolated tall trees | Uniform stands of shorter trees |
| Open meadows and exposed saddles | Depressions and valleys |
| Water and wet gullies | Dry ground away from drainages |
| Cave mouths and overhangs | Deep shelter or a building |
| Metal fences, cables, and poles | Distance from all conductors |