Weather Basics for Adventure Planning

Sure, the concept is simple: check the weather before you go. But exactly what variables should you check? What resources should you use? How can you predict weather in the high mountains or remote places away from cities? How can you read weather on your own while on the go? These are all questions that even experienced adventurers sometimes struggle with.

To help, we've broken down weather planning into a few easy steps. Here you'll find our suggestions on what forecasts to pay attention to as well as the best apps and websites to find them.

Planning Ahead

The first step is always to check the weather before you go out so you know how to pack and what to expect. The relevant metrics for most outdoor activities are:

Temperature
Precipitation
Cloud cover
Wind speed and direction

These major variables are clearly visible in just about any forecast. There are also some other, less commonly understood factors that you may want to check depending on your plans:

First/last light times: A bit longer than the time from sunrise to sunset, this is the time within which you can reasonably see without a headlamp.
Visibility: Distance you can see to the horizon.
Humidity: Amount of water vapor in the air, usually expressed as a percent. Very humid air makes hot temperatures feel hotter and cold temperatures feel colder.
Dew point: Temperature below which water vapor condenses out of the air and forms dew, which varies with humidity and atmospheric pressure. In cold weather, reaching dew point can mean wet and/or frozen gear overnight.
Atmospheric Pressure: Useful for predicting weather on the go, rising atmospheric pressure generally means stable and dry conditions, while falling pressure generally means bad weather might move in.

Plenty of apps and websites are good for checking basic forecasts. National Weather Service, Weather Underground, DarkSky, and The Weather Channel are good ones that also have mobile app versions. The onX Backcountry GPS app also reports weather conditions from the nearest weather station to your current location or wherever you point to on the map. Most of these can tell you about the less commonly used variables listed above, as well.

Wind

Just about everyone is familiar with temperature, precipitation, and clouds in a forecast, but an important variable that is sometimes overlooked is wind. For some adventures, wind can make the difference between a great day and a terrible one. Most standard forecasts also include wind, so don't forget to check it.

When you see a compass direction listed with the wind, this is always the direction wind is coming from, not blowing toward. If you see an arrow, it represents the compass direction that the wind is blowing in. For example, a "northwest wind" blows from the northwest toward the southeast, and might be represented by an arrow pointing toward the southeast.

Wind speed is also worth noting, but many people aren't familiar with how the numbers translate to what you actually feel. If you see a forecast for wind gusts, this describes the speed of momentary bursts of air that are 10 or more mph above the base average wind speed for the day. Here's a rule-of-thumb guide to wind speeds:

Less than 8 mph is generally considered a light breeze. When sustained, however, this can still be enough to make flatwater paddling or biking significantly more difficult if traveling into the wind.
8-12 mph is a light wind that rustles leaves and small branches.
12-20 mph is very noticeable, swaying branches and blowing around small, loose objects.
20-25 mph makes small trees sway, whitecaps form on lakes and small waves break on shore.
25-30 mph may cause whole trees to sway and larger objects to blow around.
30 mph and greater is difficult to walk against.
40 mph and greater may make it difficult to even stand up, and a gust of this speed is enough to knock a grown person off balance.
50 mph can be dangerous. It's enough to make objects airborne projectiles.

Precipitation

When you see percent chance of rain in a forecast, you are reading a measurement of PoP (Probability of Precipitation). This is not exactly the probability of you yourself getting wet by standing in a given spot. It is actually the product of an equation that combines confidence of precipitation occurring and the geographic area of the forecast. You won't necessarily know the area of the forecast by checking the weather for one given spot, however, so the most reasonable interpretation of a "40% chance of rain" is that you have a more or less 40% chance of seeing precipitation somewhere near you, though maybe not right on you.

This may sound like good news, if a 40% percent chance of rain means you actually have less than a 40% chance of getting wet. Important to consider, however, is where you wil will be on the landscape. If you check the weather forecast for the town in a valley nearest your trailhead and it says 40% chance of rain, but you are hiking up into the mountains, your chances of getting wet are probably higher than that in reality. High elevations tend to get more moisture than lower. Even though it may be a 40% chance of rain for that area, it may not be evenly distributed. All weather, not just precipitation, can vary dramatically with elevation, even over short distances.

That raises the question of how to check the weather for high mountains or any places that are too remote to have weather stations nearby. Luckily, there are resources you can use to find forecasts far from cities or weather stations. They should always be taken with a grain of salt, however.

Point Forecasts

Point forecasts are weather predictions for a given spot on a map, regardless of how far it is from any weather stations. When you check the weather for a city or town, you are likely seeing an area forecast based on multiple weather stations in the vicinity as well as regional models. Point forecasts are technically area forecasts as well, but they are calculated for areas as small as 1 square mile. In remote locations, They are based more heavily on regional models and topography than on current readings because without nearby weather stations, readings are not available. If you are traveling far away from populated places, however, a point forecast may be the best resource available.

For spots within the United States, the National Weather Service is a great resource. To get a point forecast, go to the weather.gov homepage and enter the name of the closest town to get a local forecast. Next, scroll down a bit to find the map box. Scroll around on the map and click anywhere to get a point forecast for that spot.

These additional online resources build more specialized forecasts that you may find useful, and they work outside the U.S. as well:

Mountain Forecast makes it easy to find point forecasts for particular peaks, and it even breaks down forecasts by elevation.
Windy.com is best for current wind conditions, but it also details other conditions and gives forecasts.
Storm (mobile app by Weather Underground) highlights rain, snow, and lightning conditions within live radar and also shows forecasts.
DarkSky's mobile version provides short-range point forecasts for exactly where you are when using the app.