If you've spent much time in Colorado's high mountains, you know the weather can change fast. A morning that starts calm and clear can turn into building clouds, strong wind, rain, hail, lightning or even snow before you make it back below treeline. That's why checking the forecast needs to be part of the plan before you leave home. If the weather does not support the plan, change the plan.
NOAA/National Weather Service forecasts are a good primary source for Colorado mountain weather because you can check forecasts for specific locations instead of only looking at the nearest town. This is important because weather can be very different between a town, a trailhead, a high basin and a summit ridge. Also look for the actual elevation listed for the point forecast being viewed (beneath the small forecast area map). NOAA determines that elevation from an average within the highlighted forecast area, so it is not necessarily the exact elevation of a peak you selected or searched for directly on NOAA.
The remainder of this page explains the main parts of a NOAA point forecast and what to look for when planning your hike. The goal is not to predict the weather perfectly, but to understand the forecast well enough to decide whether your route, timing and group make sense for the conditions.
Here's an example NOAA forecast page, for 14er Mount Elbert. The daily (icons) summary gives you a quick overview and the detailed forecast area gives you more information about the timing, winds, etc.:
The main NOAA forecast gives you a quick overview of the next several days. This is useful for spotting obvious problems: storms, high winds, snow, very cold temperatures or a changing weather pattern. But the daily forecast is only the first step. For mountain planning, the timing of the weather is often more important than the general daily summary.
A town forecast can be useful for the drive, trailhead and general weather pattern, but do not base a mountain decision only on town weather. A summit, ridge or high basin may be colder, windier and more exposed to storms. If the town forecast looks marginal, the mountain forecast may be worse.
On NOAA, check where the forecast point is located. The small map on the forecast page shows the exact spot being used for that forecast. If the point is too far from your route, too low in elevation or on the wrong side of a mountain range, the forecast may not represent the conditions you will actually encounter.
To adjust your forecast area slightly, click/tap the map to move the forecast point:
If needed, move the forecast point closer to the peak, ridge, basin or trailhead area you plan to visit. This does not make the forecast perfect, but it usually gives you a better picture than using a lower-elevation town forecast several miles away.
Also pay attention to elevation. A forecast point near 9,500 feet may not fully reflect what you will experience at 13,000 or 14,000 feet. Expect colder temperatures, stronger wind and more exposure as you climb higher.
The daily forecast is only a summary. For mountain planning, the hourly forecast is one of the most useful parts of the NOAA page. It helps you understand the weather window for your hike: when storms may start, when wind may increase, when precipitation may arrive and whether temperatures may drop during the day.
Depending on the NOAA page layout on your device, you may need to scroll down or open the hourly forecast link to see this chart.
The hourly chart breaks the forecast into separate graphs for temperature, precipitation, thunder, wind, snow and other details. This is probably the most useful part of the NOAA page for mountain planning. Instead of giving one broad forecast for the whole day, it breaks the weather into different components over time. Notice the "Back 2 Days" and "Forward 2 Days" buttons at the top:
The hourly chart can look busy at first, but it is worth studying. Instead of giving one broad forecast for the whole day, it breaks the weather into different components over time. You may see separate rows or graphs for temperature, wind speed, wind gusts, sky cover, rain potential, snow potential, thunderstorm chances and other weather factors.
This is especially helpful on 14ers because a forecast that says “chance of thunderstorms” does not tell the whole story. Storms expected at 4 p.m. may allow for a very early, short hike. Storms expected at 10 a.m. are a clear no-go for a long route. The timing matters.
Look across the chart from morning through afternoon and compare the forecast to your expected hiking timeline. If thunder, precipitation or strong winds increase during the time you expect to be on a summit, ridge or exposed slope, your plan should change.
You do not need to be a meteorologist. Focus on the forecast details that can quickly affect safety in the mountains.
Thunderstorms and lightning are the biggest summer concern. Look for when thunderstorm chances begin, not just whether storms are mentioned somewhere in the day. If thunderstorm chances rise while you expect to be above treeline, that is a serious warning sign. Your goal is to be off summits, ridges and exposed terrain before storms develop.
Rain, hail and precipitation can make rock, trail and tundra slippery. Rain can also make a descent slower than expected, and hail or graupel can quickly create slick conditions on rock. A small chance of precipitation may not sound like much, but when combined with thunder, cold temperatures or difficult terrain, it matters.
Snow can change the route completely. In spring, early summer, fall and winter, check whether snow is forecast and whether recent weather may have left snow or ice on the route. Even a small amount of new snow can hide trail details, make rock slippery or turn an easy route into something more serious.
Wind deserves more attention than many hikers give it. Strong wind can make ridges, saddles and summits uncomfortable or unsafe. Gusts can affect balance, make scrambling more serious and increase the risk of hypothermia when combined with cold or wet weather. Be especially cautious on exposed routes.
Temperature affects more than comfort. Temperatures near a summit can be much colder than at the trailhead, and wind can make it feel colder still. If you get wet from rain, snow or sweat, cold temperatures and wind can become dangerous quickly.
After checking the forecast, compare it to your route. The same forecast may be acceptable for one hike and a bad idea for another. A short Class 1 or Class 2 hike with quick access back below treeline is very different from a long ridge traverse, a loose Class 3 route or a remote 13er.
Think about how long you will be above treeline, how exposed the route is and how quickly you can descend if the weather changes. If the weather window is short and the route is long, choose a shorter route or stay home. If thunderstorms are expected while you will still be on exposed terrain, do not go.
Also be honest about your group. A fast, experienced group may have more options than a slower group or someone new to altitude, scrambling or long days. The forecast has to work for the whole group, not just the strongest person.
The forecast is only the starting point. Once you are on the mountain, keep watching the sky, the wind and your group. Forecasts can be wrong, storms can build earlier than expected and a route can take longer than planned.
Watch for clouds building vertically, darkening skies, sudden wind shifts, falling temperatures, distant thunder or precipitation forming nearby. If the weather is changing faster than expected, do not wait until it becomes obvious. Start descending early.
Also watch your timing. If you are moving slower than planned, your original weather window may no longer be realistic. A forecast that looked acceptable for a 10 a.m. summit may not be acceptable if you are still climbing at noon.
Turning around is not failure. It is good mountain judgment.