The end of summer triggers all sorts of coping mechanisms among hikers. Some dress in a panic, piling on giant jackets and insulated pants in anticipation of the coming winter season. Others remain in denial, clinging to their summer wardrobe in hopes that fall isn’t really here just yet.

The widespread layering confusion makes sense. After all, most hikers find it straightforward to dress for hot weather or cold weather, but shoulder seasons represent a murky meteorological limbo. In the fall, temperatures and conditions can vary widely between times of day, altitudes, and even between sun and shade. Bringing the wrong stuff will usually just leave you kind of uncomfortable and cranky. But if you get surprised by a serious rain shower, early-season flurry, or dangerous temperature drop, being underprepared could leave you at risk of hypothermia or worse. Here are the top six most common layering mistakes hikers make in fall—and how to avoid them.

1) Forgetting a jacket. 

If you start your hike on a sunny afternoon (or at a lower elevation), you might be tricked into thinking it’ll be warm all day. But days are shorter this time of year, and weather tends to be more erratic, especially at higher altitudes. Even 500 to 1,000 feet of elevation gain can make a big difference in both wind speed and temperature. Aim to bring at least a mid-layer or a lightweight puffer on all your autumn outings. A good wind shirt and a three-layer waterproof jacket (like the Torrentshell 3L from Patagonia) should also be on your list. 

2) Assuming there won’t be snow. 

In the fall, having the right footwear can make or break your hike. That’s because temperatures can drop fast. If you get stuck out in the cold with wet feet, you’re going to have a bad time. So, if your daily driver isn’t a waterproof boot, now might be the time to upgrade. (There are plenty of deals out there, but the Oboz Bridger and the Salomon X Ultra 4 are among the best options at entry-level price points.) 

It’s also smart to bring Yaktrax or some other kind of traction if you plan to venture into higher elevations. In the high country, early-season snow or ice are often possible as early as October. 

3) Dressing too warmly. 

When you start a hike on a brisk fall morning, it can be tempting to bundle up—only to get to your destination, start marching uphill, and find out those fleece-lined pants were way overkill. The best way to prepare for fall’s crazy temperature swings is to bring lots of thin layers that you can add or subtract to suit the conditions. Think: a light wool base layer and a Patagonia R1 Daily Zip Neck Jacket instead of a full-on down parka; or, quick-dry joggers like Patagonia’s Terrabonne pants (possibly with some long underwear underneath) instead of your insulated mountaineering pants.

Another tip: Opt for mid-layers and base layers with zippers, which allow you to make micro-adjustments in temperature as cloud cover, rainfall, and sunshine come and go. 

4) Skipping the sun shirt.  

Just because it’s cold, that doesn’t mean the sun’s not out. In fact, hikers commonly start ditching their sun protection as soon as the leaves start falling. And as much as we love the look of peeling noses and odd sunglass tans, there’s no safe way to recommend skipping sun gear altogether. Instead, consider bringing—at the very minimum—a ball cap and a sun shirt. For the latter, look for something that actively reflects sunlight, like the Columbia Sun Deflector, or a shirt that’s light and UV-blocking, like Patagonia’s long-sleeved Capeline top. (Bonus: A Capeline can also provide a little warmth should temps suddenly drop on you.) 

5) Wearing cotton.  

Spend enough time on the trail, and at some point you’ll see an old timer point at somebody’s white crew socks and grumble “Cotton kills!” It’s a well-worn adage, but it’s only sort of true. In the summer and in arid conditions, cotton clothing can actually be a benefit as it holds onto moisture and takes forever to dry—helping keep your body cool in serious heat. But come fall, those old timers start to sound a little wiser. That’s because cotton’s heat-sapping abilities can quickly turn into a hypothermia risk in cooler temps. So, before you go on your next fall hike, swap out your cotton clothing (especially those socks!) for wool or synthetic. Both dry faster than cotton, and retain warmth even when they’re wet. 

6) Bringing a tiny backpack. 

OK, OK, your pack isn’t exactly a layer, but it’s one of the most critical pieces of your layering system. That’s because personal temperature management is all about adding and subtracting layers. Where do all those layers go? Into your pack, of course. That means you’ll need something a bit more capacious than the little hydration pack you might rely on for summer hikes. 

For fall day-hikes, look for a pack with at least 30 liters of volume. For weekend overnights, a pack that’s 55 liters or more (like Gregory’s Katmai 55 or the Osprey Aura 65) should do. Other must-have features for shoulder seasons include: a breathable back-panel and plenty of side or back pockets for quickly stuffing your jacket as soon as the sun comes out. 

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.