Talk to anyone you know who spends lots of time in the backcountry and they’ll tell you that there’s no such thing as one-size-fits-all backpacking checklist.

Every backpacking trip has different challenges and conditions, and it’s important to understand what they are before you head out, or even start planning your gear list.

To make sure you have everything you need for your upcoming trip – and nothing you don’t – you need to have a solid understanding of what you’re heading out into. Here are the 10 most important factors you’ll need to be aware of when planning and packing for your next backpacking trip.

1. Number of People in Your Group

The size of the group you’re going out with can have a big impact on what you bring. With a larger group, you can spread group gear’s weight out across everyone and will have an easier time bringing heavier camp conveniences.

The more people in your group, the more likely you are to have someone get injured, so you’d usually want to bring a bigger, more extensive first aid kit. Make sure to bring extras for supplies like advil, immodium and gauze.

Another factor to consider with group size is what sort of cooking gear you’ll need to prepare everyone’s meals at the same time. You could all split off and make your own meals on your own stoves, but there’s something really nice about having a large stove and preparing and eating meals together.

2. Expected Daytime and Nighttime Temperatures

While most local news forecasts only show the forecast for 7-10 days out, you can often find forecast information weeks or even months ahead of time. The NOAA has a tool for finding local weather stations, and sites like aggregate historical weather data to make predictions.

If temps will be hot during the day, think about carrying more water, wearing light, cooler layers and lighter shoes and socks, so you don’t get too dehydrated on the trail.

Also think about how the temperatures will impact your sleep system. In cooler weather, you’ll want a heavier sleeping bag and ground pad to keep you insulated and warm.

3. Precipitation, Cloud Cover and Sun Forecast

Another thing to look at when checking the forecast is what the clouds will be doing. If you’re expecting storms or rain, make sure you don’t forget to pack a good shell to help you stay dry. You’ll also want to be able to understand weather report details like humidity, dew point, cloud cover, UV index and more.

Conversely, if the forecast calls for it to be relatively clear skies, make sure you wear sunscreen, a hat and sunglasses to protect yourself from UV damage.

In extreme northern or southern areas, it’s also a good idea to look at the expected sunrise and sunset times so that you have a sense of whether you’ll be hiking or doing a lot of camp chores in the dark and need a brighter headlamp.

4. Trail Conditions

In popular areas, there’s usually a site or forum that lists the current trail conditions. This will help you figure out if your expected hike will be muddy or snowy, which may require bringing extra traction or different footwear.

Also think about any river crossings you need to make and how high the river will be. A lot of places may be a small trickle in the fall, but swell to several feet deep in the spring with snowmelt, or after a big rainstorm. Consider bringing sandals to change into to make the river fords much easier.

5. Terrain

The terrain you’ll be traveling through and living in will have a huge impact on what sort of gear you can bring. For example, in alpine areas you won’t have much use for a hammock (no strong tress to hang it from) and you may need to carefully consider how to handle cooking and waste.

You might also consider tougher, heavier gear if you know you’ll be exposed to a lot of abrasion from rocks or sand. If the terrain is steep or snowy, you might need specialized gear to handle those natural hazards.

6. Water Availability

How far will you have to travel between water sources? The frequency of refill options will have an impact on the water carrying capacity you should have, especially if your route will be hot and exposed.

You should also have a sense of whether the water sources you’ll be using are generally clear and free flowing or whether they’re more murky, stagnant spots. This could impact the filtration and purification system you’ll need to bring.

7. Animal Threats

If you’ll be spending any time in warm, humid areas without much wind, you’ll likely need to pack bug spray to help fend off mosquitoes, black flies and other pests. You can also treat your clothing with permethrin ahead of time to act as an extra insect shield while you’re hiking or lounging in camp.

In some areas, bears are a common nuisance and you may be required to carry bear spray. Make sure you keep it handy on your hipbelt or shoulder strap, and maybe also consider wearing a bear bell to decrease the chance of a surprise encounter.

You may also be required to pack your food in a bear canister to keep it safe and keep bears from wandering through your camp. Even if you’re not in a bear area, you should bring a few dozen feet of parachute cord and a stuff sack to hang your food up in a tree at night. This helps protect it from bears, as well as mice, squirrels and other smaller pests.

8. Expected Trail Mileage

If you’re going to be hiking for more than 10 miles in a day, you’ll probably want to consider “ultralight” gear to lighten your load and make your trek more enjoyable.

Another piece of gear I recommend to anyone tackling serious mileage is a good set of hiking poles. They help take strain off your knees with each step, and also help you keep your balance and cadence.

9. Fire Restrictions

Many popular areas prohibit open fires and may place restrictions on the types of cooking or stove types you’re allowed to use. Some places allow fires but may not have a good supply of deadfall for collecting kindling or tinder, requiring you to bring your own.

Conversely, some places have restrictions on what type of firewood you’re allowed to bring into the area, to reduce the chance of infectious diseases spreading to local trees. In this areas, you’ll likely have to buy firewood locally.

10. Remoteness

What is your plan if someone has a backcountry medical emergency? Will you be able to call 911 from your cell phone, or will you need some sort of satellite messenger to send a distress signal?

You should also consider whether there will be lots of other hikers around who would come across you quickly, or whether you’d potentially be stranded out by yourself for hours.

Feeling overwhelmed by all that you have to consider? I just released a free tool that automatically generates backpacking checklists for your trip, based on a number of the criteria that I listed in this article.