Trip planning research: My go-to resources

A six-week hike on the Pacific Crest Trail, starting at the US-Mexico border on June 6, 2006, sounded hot and dry to me. But fifteen years ago I had no experience with southern California or deserts generally, so I didn’t know how to properly prepare my gear, supplies and skills.

What clothing, sleeping bag, and shelter should I use? What foods would be most heat-resistant, and how much water capacity should I have? And what measures could help reduce the sting of scorching mid-day temperatures?

Not knowing where else to get information, I sent questions to the PCT-L, an online email list that at the time was the premier source of news, conversation, and advice about the Pacific Crest Trail.

Ten minutes later, a member pointed me to the Western Regional Climate Center (now part of the National Centers for Environmental Information), which had what I needed. His answer did not give me the specific information for which I’d hoped, but the learned self-reliance served me better for every trip thereafter. Give a man a fish and you feed him for the day. Teach a man to fish and you feed him for a lifetime.

I’ve written before about the importance of researching likely conditions, and the exact conditions to research. I’ve also shared a sample conditions assessment. In this post I want to highlight the resources on which I rely most heavily and regularly.


In the United States, historical temperature and precipitation data can be obtained from the National Centers for Environmental Information (NCEI), specifically using the “Climate Normals 1981-2010” database.

The website could be more intuitive, but it’s functional. Watch this video step-by-step instructions.

NCEI is best for far-out planning. Starting 7-10 days out from a trip, switch to the National Weather Service (NWS) to better tailor your preparations, following the instructions in the same tutorial.

Screenshot of the NCEI mapping tool used to find monthly climate normals

For years I obtained sun and moon data from the US Navy. But it shut down this service, so now I rely on

Find sunrise and sunset here.

And the moon cycle here.

Sun graph for Anaktuvuk Pass, Alaska, which enjoys 24 hours of daylight in the summer

CalTopo and GaiaGPS

CalTopo started as a desktop-first mapping platform and later launched an app. It remains dominant for at-home trip planning and map printing. Gaia GPS started as a mobile app, and built functionality into its website afterwards. Its best use is still in the field.

A subscription to both platforms is ideal. But if you want to use just one, select the platform that is strongest on your device-of-choice. Personally, I lean towards CalTopo because I plan my trips at home on my desktop computer and because I prefer paper maps in the field. If you’re more mobile-based, then Gaia GPS would be the better pick.

Both platforms will give you access to topographic maps, satellite imagery, and various other data layers (e.g. snow coverage, active and historical fires, slope aspects, and more), which can help inform your research on:

  • Footing
  • Vegetation
  • Navigational aids
  • Water availability
  • Sun exposure
  • Remoteness
  • Natural hazards like avalanches, river fords, high altitude, wildfires, and lingering snowfields
Sentinel satellite imagery of Yosemite National Park showing the snowpack in June 2019, viewed in CalTopo
Screenshot of Gaia GPS website showing the NG Trails Illustrated map of Rocky Mountain National Park with the fire history overlay showing the East Troublesome Fire of 2020.

Snow surveys

To best understand where there’s snow right now, use the aforementioned snow satellite layers in CalTopo and Gaia. Another useful platform with this data is snowEvaluator.

But to best understand the state of the current snowpack and how it compares to historical norms, other resources are needed.

In most of the West and Alaska, pull data from SNOTEL. I specifically like the state-level maps of snow water equivalent (SWE) and snow depth.

California has its own program, the California Cooperative Snow Surveys. Among its data, I most like the interactive snowpack plots.

River monitoring

If your route involves un-bridged crossings of creeks or rivers that could be hazardous, check the flow levels of those creeks or rivers, or nearby creeks or rivers that probably share a similar pattern.

In most of the US, the best resource is the National Water Information System from the USGS.

California has its own river monitoring program. In an earlier post I linked a half-dozen representative monitoring stations for the High Sierra.

Land agencies, trail associations, and public services

Information from these resources tends to be more conservative, by-the-book, and safety-minded than what you’ll find elsewhere. It’s also official or quasi-official, and it shouldn’t be discounted.

The comprehensiveness and quality of information on land agency websites varies tremendously. In general, heavily visited areas like Yellowstone get more attention than lesser known spots like Kobuk Valley. On the best maintained sites, you will find information about:

  • Overnight food storage regulations,
  • Trail and trailhead descriptions,
  • Updated trail conditions, hazards, and closures
  • General backcountry descriptions
  • Natural history, including climate zones and geology

Trail associations like the Colorado Trail Foundation are another good source for official regulations and trail-tested guidance, though for a very specific backcountry experience.

Finally, there are avalanche information centers like the CAIC for most western US states. This hazard is not usually a consideration for 3-season backpacking, for anyone wandering mountainous backcountry during the winter it most definitely is.

Print and online guides

Today a handful of authoritative guidebooks are still available only in print form. Secor’s The High Sierra, Roper’s Sierra High Route, Kelsey’s Wind River Mountains, Pallister’s Beyond Trails in the Wind River Mountains, Allen’s Canyoneering 3, and Roach’s Colorado’s Indian Peaks come to mind. Copies of each still are on my bookshelf because no better reference exists.

But it’s a decreasing number, as online sources — like the Guthook app, AllTrails, High Sierra Topix, and my own guidebook downloads — chip away at the exclusivity of older printed content, create new backcountry experiences for a digital generation, and offer more updated (and even real-time) information.

A pre-trip perusing of these texts, maps, water charts, and datasheets will often turn up information or tips about:

  • Footing
  • Vegetation
  • Navigational aids
  • Water availability
  • Problematic wildlife
  • Insects
  • Natural hazards

Forums, blogs, YouTube, and social media

Digital platforms have grown tremendously, both in their gross quantity and their output. I don’t think it’s a stretch to say that today you could fully prepare for an Appalachian Trail thru-hike without looking anywhere else besides YouTube!

The downsides of everyone having a microphone are that (1) the signal-to-noise ratio is poor, and (2) the credibility of the source is not necessarily guaranteed. So consume carefully those trip reports, gear reviews, skills advice, and gear list shakedown comments.

Some channels like the JMT Facebook Group focus on a particular area, trail, or route, whereas others like r/Ultralight stay broad. Google will be your best friend in finding channels that are relevant to your itinerary.

Knowledgeable users

Online resources have made it easier and faster to research the likely environmental and route conditions on your backpacking trip. This is where I start, and it’s how I get three-fourths of the way there.

But to fill in the gaps and to confirm information that I’ve found but don’t entirely trust, I rely on direct conversations with people who have valuable first-hand information but who may not have shared what they know (or everything they know) in a public place, like about an unmapped spring, a fast game trail, a strong tidal current, or the technical difficulty of a dicey-looking pass.

Prior to past trips, I’ve called and emailed park rangers, previous hikers, experienced locals, nearby gear shops and guides, lodge owners, trail stewards and trail angels, bush pilots, village elders, postmasters, and chambers of commerce. Get creative here, and keep dialing until you learn what you need to know.

As someone who occasionally is contacted as one of these resources, I’d advise that you do some homework before making contact. I almost always respond to a well informed inquiry, but I almost never respond to someone looking for basic information that could have been answered in seconds with a Google search.

With Roman Dial at our Wolverine Creek campsite, Brooks Range, Alaska

What resources do you rely on most often to research trip conditions? Leave a comment.

Posted in , on February 22, 2021


  1. Cathy on February 23, 2021 at 6:27 am

    “Today a handful of authoritative guidebooks are still available only in print form. Secor’s The High Sierra, Roper’s Sierra High Route, Kelsey’s Wind River Mountains, Pallister’s Beyond Trails in the Wind River Mountains, Allen’s Canyoneering 3, and Roach’s Colorado’s Indian Peaks come to mind. Copies of each are”

    Your comment cut off in the middle. Copies of each are ?

    • Andrew Skurka on February 23, 2021 at 8:38 am

      Not sure how that happened, maybe from working on this post from two different computers. Fixed now.

    • Ross on February 24, 2021 at 6:56 am

      Have you ever used SunCalc for sun and moon data? I particularly like that it shows you direction of the sun as well, so you can better plan where youll have late evening light, or where you’ll get into the morning light quickest to warm up. Plus planning out those sunset photos ahead of time when you get the itch!

      But yea, awesome post! I’d always struggled to find good historical weather, usually just trusting whatever random result came up in Google first. Thanks for sharing!

      • Andrew Skurka on February 24, 2021 at 8:47 am

        I’ve not used SunCalc, but I did notice on CalTopo yesterday that a recently added layer is “Sun exposure,” which gives you sun/shade cover for each month in 1-hour increments.

        • Ross on February 24, 2021 at 9:23 am

          Super interesting, I hadn’t played with that feature before but just now it looked handy. Thanks!

  2. Cathy on February 23, 2021 at 9:06 am

    Thank you, Andrew!

    Your site is excellent, your Ultimate Hiker’s Gear Guide is amazing, and I am always learning something new from you.

    I wish I could do an Adventure trip with your team, but my fitness level just wouldn’t support it. (50+ female, average fitness). My backpacking experience is beyond where a Beginner trip would be interesting, but my fitness is not up to what a Moderate trip would require.

    I may take your Planning course one of these days.

    • Felipe on April 11, 2022 at 11:29 pm

      Yes you can! This is when fitness is secondary to will and perseverance. Age is only a limitant if you let it be a limitant. My father very fit man at 75 took my very unfit mom in 1000k from france to portugal by foot. He methodicly train her just walking around their house. Life is now, go out and take it!

  3. Froste on February 24, 2021 at 5:21 pm

    I used to track snow coverage for shoulder season trips. Planet own and operate many small satellites that provide low resolution but frequently updated aerial imagery. Depending on cloud coverage I could usually see the area I was planning to visit with daily updates. THey also provide a month by month stitched image. Unfortunately the free service has been recently suspended. Does anyone know about similar services?

  4. Jim on February 24, 2021 at 7:34 pm

    I like “Gaisma” for sun and moon hours:

  5. George on February 24, 2021 at 8:30 pm

    I’ve enjoyed using for far out research on expected weather conditions. It includes all the primary info needed evaluate expected conditions, such as temp, precipitation, wind, cloud cover, humidity, sun/moon, and water temps.

  6. James C on March 12, 2021 at 10:48 am

    What about the river gages that USGS monitors for rivers? For example ( we had a warm period here in New Hampshire and the Pemi river flow and height saw a spike the last two days. Which during this time of year could be an indication that some ice bridges for water crossings in the Pemi and it’s up-river tributary brooks and streams have collapsed and some rivers might be difficult to ford in the next few days.

    • Andrew Skurka on March 12, 2021 at 11:12 am

      That’s a great resource, and something I completely forgot to add (as well as snow), fixed now.

  7. Douglas on May 1, 2021 at 1:18 pm

    What resources do you recommend for finding historic low and high temps as opposed to average historic temps? works but is tedious, requiring searching individual dates.

    • Andrew Skurka on May 3, 2021 at 9:57 am

      NCEI and NWS, as mentioned

  8. Gil Anspacher on June 14, 2021 at 12:47 am

    Thoughts on CalTopo iOS mobile app now vs Gaia, especially with paper from CalTopo as the primary source? It seems pretty good testing at home. And Gaia has been our goto for a long time. Not having to export, import and sync would be nice. If yo still point towards Gaia, what are the main features that point this way?


    • Andrew Skurka on June 15, 2021 at 12:43 am

      The CalTopo app is now fully functional, and the sync with the website (where I do all the route planning beforehand) is really convenient.

      Gaia is still a generally more refined app, reflecting its respective history and focus. The one place I’d say CalTopo does a notably better job is the download maps feature — CalTopo seems more intuitive and certain.

      • Cathy on June 26, 2021 at 8:36 pm

        I cannot get the CalTopo app to scroll down through a long list of Map Items. It seems to be a bug that appeared a few months ago and hasn’t been fixed. It leaves me with no way to select or deselect folders or items for display.

        Unfortunately that is a big enough issue to make the Android app unusable, though I love their browser-based web site for trip planning and printing maps.

        • Andrew Skurka on July 6, 2021 at 5:49 pm

          I was just using the CalTopo app in Alaska, and didn’t experience this problem. It scrolled through my item lists (which are very long on some maps) just fine.

  9. Gil Anspacher on July 13, 2021 at 1:58 pm

    I used CalTopo on iOS on YHR-South (just returned). It was as good or better than Gaia. No issues with scrolling through item lists. The bearing feature is really helpful.

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