Rain happens, so prepare for your wedding day by bringing the following along just in case. You can always leave it in the car if we know for sure it won't rain (or rain much).

Rain jacket
Clear umbrellas. These can be found on Amazon.com, Target, Belk, Walmart, etc.
Waterproof hiking shoes.
Vibram-soled (or similar) shoes. Get some shoes or boots that you can easily move in, but also confidently step on wet roots and rocks. Trust me - it'll be way more comfortable.

Find a comfortable backpack that can hold you and your partner's gear - or two medium sized one's for each of you. Water resistant packs with comfortable straps shoulder straps, a hydration pouch, and breathability are nice to have. If you plan to change into your suit or dress at the summit or other destination, some folks do the following:
1. If possible, use a backpack that opens up like a luggage suitcase. It makes packing the items easier and helps minimize wrinkles.
2. Additionally, you can minimize wrinkles on your pants and jacket by placing material between your suit coat and pants. Packing the two things separately is also helpful. Products like "Downy Wrinkle Releaser" (or other brands) can be found in a travel size which easily fit in a backpack.
3. Fold (don't roll) your suit. Unlike other clothing, suits don't work well with the typical travel "roll" for suitcases. It's a suit afterall - not a casual t-shirt.
4. Packing cubes and shoe bags can also help save space and keep things tidy and clean, but I personally recommend folks just leave the fancy dress shoes at home for an adventure elopement. Not only are they uncomfortable to scramble around in, they add extra weight, take up precious space in your pack, and they sometimes look a little too fancy for a mountainous elopement. But, if you're jazzed about them - bring them! We can make it work.
5. If you are bringing dress shoes along, pack them at the bottom of the pack and place the suit jacket after. If you don't have a dry cleaner bag to protect the jacket, another option is to turn the jacket inside out and carefully fold it in half. From the site for Knack Bags, they recommend you 'pop both shoulders inside out (the arms will now be on the inside of the coat and not the outside like normal). Then, fold the suit coat in half so that both lapels touch. Most suits have a silk-like lining fabric that can play the part of the tissue paper or dry cleaning bag in a pinch.'

In my experience, mountain weather can be notoriously difficult to predict more than a day or two in advance. For that reason, it's greatly advised that couple's know the season and dress appropriate to the area. That means in spring, fall, winter - and sometimes even summer, pack a windbreaker or other layers. In cooler months, ear muffs work well to keep ears warm while keeping hair looking great.

Gloves are also nice to have if you get windy and cold conditions!

Depending on the length of your day in the mountains, always pack water or other hydrating fluids along. Brands like Nuun make electrolyte tablets that can be added to hydration packs or water bottles. It's a great way to keep hydrated on a warm hike/day - which is super important.

Note: I do recommend bottles with straws be left unclosed until the tablet dissolves as they build pressure and create geysers in your car! How do I know? I've had that happen a few times because I've forgotten about that part.

I also highly recommend Camelbak type water-bladders. They pack down when they're empty and/or integrate easily into most packs.

Depending on temperatures and difficulty of the hike(s), I would make sure to pack along a few 32oz bottles or hydration bags per/person. If we change locations, you can always hydrate up between trailheads to top yourself off, but if it's a long day out and you're carrying everything along (and won't be back for several hours), the current recommendations I've read say to carry approximately 1L (litre) per hour of hiking per person. If it's especially warm, bring more!

Beyond drinking plenty of fluids, consuming enough calories throughout the day is also key to staying comfortable and energized while out on your big day in the mountains.
1. Snacks. Bars, or other small, packable items. See: Trader Joe’s. :)
2. Charcuterie. Sometimes you crave something less sweet - consider bringing bread, olives, cheeses, cured meats, or your favorite vegetarian/vegan options.

Headlamps are super nice to have for hiking out post-sunset or hiking in pre-sunrise. It keeps your hands free should you need to carry anything, and for that reason makes for a safer experience in case the hike is slippery or otherwise insecure as you hike. Some great brands making headlamps are: Petzl, Black Diamond, etc. (I recommend ones that have internal batteries and can be charged in a vehicle if you need to.)

I recommend warm (2000-2200K color temp lights) like some of the Barebones Living ones, etc. They look nice and work well. You could probably return if they aren't damaged, too.

Popping champagne (or San Pelegrino) looks awesome in photos. Consider bringing a bottle of something you can enjoy together!

Add that personal touch by bringing something you've had before and both love!

Anything you want to bring that's uniquely 'you'. Photos, keepsakes, etc., you may want included in the day. This is a suggestion and not a 'must-bring' - but having that extra bit of personal touch is pretty amazing for photos and commemorating the day in a special way.

Consider bringing a local (see my vendor page for local options) or synthetic flowers along. They look great in photos and give you something to hold and use for different photos.

Synthetic ones - silk, wood, etc., are surprisingly life-like and can take the pressure off keeping the flowers from getting damaged, wilted, etc., over the course of a longer day. Afloral (and other companies) do pretty amazing work.

Make sure you have the coordinates or exact location address for the trailhead and any other locations you’re visiting. In addition - don’t just rely on cell service either Make sure to download the map directions to your phone so that if reception is spotty for you at any point, you are covered.

Note: If you’re including guests, make sure anyone driving along has the directions to the location saved to their devices as well. Inform any guests of your plans too - this includes all the details of the day so they come as prepared as you!

Make sure any vehicles joining us have filled tanks or topped off batteries the night prior.

Any unexpected stops (like finding a gas station in a rural area) create the potential for unscheduled delays and can affect the timeline. Arrive with that task completed! :)