Get the forecast for where you'll actually be
Valley-town forecasts can be wildly off for a ridge 4,000 feet higher. Use a point forecast (the NWS lets you click an exact spot; mountain-specific services model elevation) for your trailhead and your high point. Temperature drops roughly 3–5°F per 1,000 feet of gain, and wind increases sharply with elevation.
Read the trend, not just the snapshot
Falling barometric pressure signals incoming unsettled weather; steady or rising pressure signals stability. Many watches and phone barometers show the trend. A fast drop over a few hours is a stronger warning than any single-day icon.
Look at the whole arc: a 20% chance of afternoon storms every day for three days is a pattern, and afternoon convection in the mountains is predictable enough to plan around — summit early, be off exposed ridges by early afternoon.
Watch the sky as a second forecast
Clouds are data. High wispy cirrus often precede a front by a day. Building, cauliflower-shaped cumulus through the morning is the classic setup for afternoon thunderstorms — when they start growing vertically fast, it's time to get off high, exposed terrain.
The mountain rule for lightning: if you can hear thunder, you're already within strike range. Descend before it arrives, not after.
- ✓Use a point forecast for your high point, not the valley.
- ✓Falling pressure = trouble coming; rising = stability.
- ✓Summit early; be off ridges before afternoon storms build.
- ✓Hear thunder? You're in range — descend now.