Preparing for the climb is very important, not only getting physically fit for the task, but also wearing and bringing proper clothing, food, water, and other needed gear.
Get yourself ready!
I am not an athlete, but I do hike several times a year, often in the mountains. I am in fairly good cardiovascular shape. My muscular strength is about average. When climbing Mt St Helens, the round-trip hike for me takes below 8 hours. It is hard on me, and I have to take several short breaks. Especially the last part, approaching the crater rim, it feels as I hardly can make it. Sure, it is not a leisure walk, the climb does wear me out, but I can still make it. Usually, my calf muscles have been sore a day or two after the climb, though, but that has improved over the years, probably because i have done more mountain hiking.
The better shape you are in, the easier the climb will be. On my climbs, I see people in better athletic shape cruising past me with ease. If you have any health issues, you need to check with your physician first. If you have bad knees, you won’t make it, since there is a lot of “jumping” and climbing over boulders.
If you aren’t already in good shape, start running and/or hiking, especially in hilly terrain. One excellent mountain trail is the first, steep part of the Bells Mountain Trail at Moulton Falls. If you can’t make up that hill, you won’t make up Mt St Helens either!
Start hiking as soon as there is daylight, since you don’t know how long it will take for you. One time when climbing Mt St Helens with inexperienced, “out of shape” climbers, it took us 14 hours! If the pace ends up being too slow, and you feel you can’t make it to the top and back, you can always turn around, just to be safe.
Dress in layers
The climb itself will keep you hot and sweaty, and once your get closer to the top, it will be cold and windy. You need to dress in layers. Typically, the hike is started very early in the morning, when it is still cold. The first 2 miles will be gently uphill through the forest. You may want to take it easy and save your energy for the climb. That means you can dress up little warmer. Once you reach the tree line, it’s time to take off any coat or warm pants, if you are still wearing any. From then on, it’s best to be lightly clothed. Once you reach higher elevations, you can add layers as needed, for wind cover. Once you reach the top, and your body is not working hard any more, you will start freezing! So time to put the warmer layers on again!
You need a good hat, to protect from the sun! Also, wear comfortable gloves. They come in handy when climbing the boulders, and they keep your hands warm at higher elevations. And don’t forget the sunscreen!
The weather also plays a big role. On a sunny, warm and calm day, you really don’t need any warmer clothing. On the other hand, on a rainy day, you need warm and waterproof clothing, and extra clothing to replace the wet clothing. The key here is to be prepared for any probable weather conditions.
Proper footwear is important!
One of the most important pieces of clothing are your foot wear! I recommend sturdy, but comfortable hiking boots. Many of my hiking partners prefer regular walking/hiking shoes. The shoes are lighter and more comfortable. The boots are better in snow, in case you are walking in the snow, and they are also better if you are jumping on the boulders. Close to the top, you are walking in ash, and you don’t want the fine ash to get inside your footwear! Gaiters are recommended, although I have never worn gaiters myself when climbing Mt St Helens.
The most important part about the footwear is that the they fit properly and do not create any blisters on your feet! If you buy new shoes or boots, make sure you break them in well before the climb, so there wont be any surprise foot problems. When you get sand inside your boots, stop and dump it out before they cause blisters. If you get blisters on your feet during the climb, it could totally ruin your day.
The back-pack, food and water, and emergency supplies
Unless you are very strong and in top shape, and don’t mind the weight, keep your backpack as light as possible, don’t bring stuff you don’t need. So choose your layers of clothing wisely.
Choose your backpack based on how much stuff you want to carry. I see many climbers carrying multi-day backpacks loaded to the brim, and that’s perfectly fine, as long as they are able to carry it. I use a day pack, containing extra clothing, food, water, and some basic emergency supplies.
My emergency supplies are: Thermal blanket, flash light and extra batteries, first-aid kit and a lighter
Eat a good breakfast before the hike, you need the energy. Bring some easily accessible snack to provide energy during the hike. Bring some lunch for the break at the top. Bring plenty of water, especially on a warm, sunny day!
Wear sunglasses! Goggles are also recommended, since the wind on the top sometimes stirs the ash around. I brought goggles a couple times, but didn’t need to use them.
Many, if not most, people bring trekking poles. I don’t always use them. When I bring them, they seem to often be in my way. They are usually telescope-style, so I can always stash them on my back pack. The poles do help keeping the balance, especially on the boulders.
Another recommended equipment is an ice axe. I have never brought one with me though. It would be useful if you hike on a glacier, or is used as brake when glissading. Some people like to glissade on the way down. If you want to do that, bring an ice axe, and a piece of plastic to sit on. You could always use the trekking poles as break too, but it won’t help you if your speed goes out of control.
And then there is all the electronics: Phone (most likely doesn’t work up there), GPS, camera, camcorder. The electronics have to be well protected, so they don’t get bumped against the boulders, or get ruined by dust.