How To Tell If There Is Snow On The Trail

How to Tell If There Is Snow On the Trail

In This Guide
  • Using SNODAS Snow Depth Map Overlays
  • Understanding Snow & Mountain Weather
  • Overlaying Recent Satellite Photos on the Map
  • How to Check For Avalanche Risk
  • Sources for Local Trail Conditions

Every winter, I get a ton of emails asking me if there’s snow on the trails that I create guides for. The answer is that I usually don’t know the conditions unless I’ve been there recently, and unless you go there yourself, it’s impossible to know the conditions for certain. But there are some high and low tech ways  to make an educated guess about the snow and trail conditions that I use all the time. It’s not perfect, but generally, it will give you a good idea of whether you’ll encounter snow on the trail for your hike.

Even experienced hikers die hiking in winter conditions. Whether you’re looking for snow or avoiding it, hike responsibly and within your limits. Get experience hiking in the snow on easy trails first. Prepare for all conditions, understand the risks (such as avalanche zones), and have the right gear. No hike is worth risking your life for.

Checking For Snow on the Trail Video

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Past and Future Weather Reports

The first and easy thing to do is to check the weather. If it’s snowing in the area of your hike, there’s probably snow there. If you see snow that’s moved past the area, find a historic radar over the area of your hike and see if snow passed over it.

Caltopo Recent Precipitation
The free CalTopo website offers 24 and 48 hour snow overlays so that you can see how much fresh snow fell. Just switch it on in the panel on the right of the screen.
Caltopo Snow Forecast
CalTopo also offers a snow forecast at different intervals. It’s not very pretty, but it gets the job done.
Gaia Snow Forecast
The GaiaGPS website and app offers a snow forecast that you can overlay onto trail maps. Unfortunately, it requires a premium membership, but it is an easier visualization than the CalTopo setup.

If you want a premium Gaia GPS membership, HikingGuy readers get a discount. Just visit my gear page for the link.

I also recommend checking the weather for summits or maximum elevations of your hike. Most weather stations are in populated areas, so it can be challenging to find the weather for the backcountry.

Find a Vantage Point

This is a pretty low-tech approach and won’t always be applicable to your hike, but just doing a visual scan of the area can usually offer an idea of the snow cover. In Southern California there are a ton of vantage points that let you see the high mountains. If they have snow, chances are your hike will have it too.

La Skyline Mountains2
From many points around Southern California you can see the mountains.

If you don’t live close to the area that you are checking for snow, search Instagram for the location. If there’s snow in the area, you can be pretty sure that people are posting pictures.


The NOAA offers a map layer of snow data called SNODAS, the Snow Data Assimilation System. In a nutshell, it’s data that predicts the snow depth over the United States. It’s based on a sophisticated computer model that “integrate[s] snow data from satellite and airborne platforms, and ground stations.” It takes many factors in accounts including solid and liquid precipitation, temperature, snowmelt, blowing snow, and existing snowpack. The snow depth is available as color-coded data that users can overlay onto their own maps. It’s updated every 24 hours. In my anecdotal observations I’ve noticed that it’s fairly accurate, especially when used in conjunction with high-resolution satellite photos (more later). You can do a deep dive on the SNODAS model here.

You can see the SNODAS snow layer in action on the USDA Forest Service map here.

The SNODAS model isn’t good at accounting for shade and sun exposure. Generally use it as a guide and know that north facing slopes will generally have much more snow for longer than slopes exposed to the sun.

Gaia GPS SNODAS Snow Layer

Gaia GPS is a navigation tool and application with web, iPhone, and Android versions. It’s a powerful navigation system that also lets you check for snow cover when you have a premium membership. The SNODAS snow layer can be added to your map. Just put it on top of the other map layers and tweak the opacity to see if there is snow on the trail.

Gaiagps Snow Layers
If you look in the upper left-hand corner at my map layers, you can see that I’ve added “Snow Depth” which comes from NOAA SNODAS data. The snow data layer is overlaying the trail map and I’ve adjusted the opacity so that I can see both maps.
Gaiagps Snow Layer Detail
Here I’ve zoomed in and you can see the overlay on top of the trail detail. The key on the left tells you how much snow is on the ground.
Screen Shot 2019 12 02 At 11.42.19
Here’s Santiago Peak (shown in the video) after a few days of snowmelt. I just hiked this yesterday and can confirm that the snow coverage map is very accurate here. The summit had about 3 inches of snow as indicated by the green snow coverage here.

CalTopo Custom SNODAS Snow Layer

If you don’t have a premium Gaia GPS membership you can grab the same data with the free CalTopo website. It’s not as elegant but it does the trick. You just have to do a little bit of setup.

Caltopo Add New Layer
On the main Caltopo screen, click “New Layer” and “Custom Source.”
Caltopo Snow Settings
Use these settings for the custom layer then save.
Caltopo Snow Layer
The new layer (whatever you named it) will show up on the right.
Caltopo Snow Layer. Onjpg
Turning it on will give you the overlay of snow. Notice that it’s not as smooth as GaiaGPS and you can’t tweak the opacity. But you can see the snow.

You can create a free CalTopo account and save the SNODAS layer so that you always have it handy.

CalTopo SnoTel Stations

The US Department of Agriculture also has over 800 remote snow measurement systems in watersheds around the United States called SnoTel. You can view each station’s readings on CalTopo with the built-in SnoTel Data later. Just click the layer on, then click on one of the stations on the map for snowfall over the last 1-7 days.

Caltopo Snotel
The bottom graph shows the snow depth of the recent snowfall.

CalTopo Recent Satellite Photography

Checking a recent satellite photo of the area where you want to hike is another great way to do snow reconnaissance. Luckily CalTopo integrates high-resolution Sentinel Satellite imagery, updated every week. I generally overlay the satellite image on top of a trail map. If there is cloud cover, the imagery is not so useful, but there is an archive of past weeks that you can search through too.

Caltopo Add Sat Image
You can overlay the recent satellite photo on top of the hiking trail map and then tweak the opacity.
Caltopo=snow On Trail
Here’s satellite photography showing snow on top of the trails.
Caltopo Snow Detail
You can zoom in on the trail and see specific areas that are covered or not covered.


Snowevaluator Screenshoot
snowEvaluator is a free tool based on Google Maps and Sentinel satellite imagery.

snowEvaluator is a free option that was built on the Earth Engine Apps platform. It uses weekly Sentinel imagery and then turns the snow cover into a false red, so it’s easier to distinguish snow from clouds. It also takes the satellite imagery with the least amount of clouds, which should help improve accuracy.

Local Reports and Imagery

Snow Reports On Reddit
Recent trail reports are great for finding out what the trails actually look like. Here I’m checking out pictures and trip reports on a Southern California hiking group on Reddit.

Looking at a map with snow data is helpful, but it doesn’t give you the condition of the trail and snow. That’s why I try to find as many local sources of information as possible, and if I don’t find them, I ask the community. Each area has its own spots where it congregates online to share, so you’ll probably have to do some searching to find them. Using the region plus “hike trip report” or “trail report” in Google should get you most of the way there. Some places to search are:

Even if the trail looks doable, the roads might be closed. Don’t forget to check local sources for any road closures.

A Quick Note On Avalanches

Understanding avalanches is a whole science in itself and I’m not going to go too deep, but there’s a quick tool you can use to make sure there isn’t avalanche risk on your hike.

Screen Shot 2019 12 03 At 05.56.21
CalTopo has a terrain shading feature that color codes steep areas that could be avalanche risks.

Once you know how much snow is on the ground, you can then take a look at steep sections along your trail. The darker terrain sections (orange to purple) are the steepest. If your trail goes beneath or on those slopes, there’s a potential avalanche risk. Note that these gradient visualizations are based on an elevation model and don’t always represent physical features that might also increase the risk of avalanche. If there is already a lot of snow on the ground, new snow can increase the likelihood of an avalanche.

Most avalanches are triggered by the victim, so knowing what conditions to look for is important. If you’re not experienced with winter hiking, you’re best avoiding any avalanche areas until you have more skills under your belt. I highly recommend this book by Bruce Tremper if you want to learn more about avalanches.

Check to find local avalanche reports near your hike.

Putting It All Together

Here’s the workflow that I use to determine if there is snow on the trail and then what to do.

  1. Get as much data as possible (using the former methods) to determine if there is snow on my hike and where.
  2. If there is snow on the route, check the avalanche risk.
  3. Check the upcoming weather and make sure there is not more snow coming.
  4. Decide “go or no go” for the hike. If I can walk 0n the trail with micro-spikes and there are no obvious dangers, I’ll go. Otherwise I know it will be more of a mountaineering exercise and not a hike.
  5. If I do go hiking and the conditions are not what I expected, I’m not afraid to turn around and call it a day. I never put myself in a situation where I have to do something dangerous.

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