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It is important to be aware of the effect of high altitudes on yourself and/or your guests. Regardless of level of fitness, some people can experience headaches, nausea, dizziness, fatigue, and shortness of breath at altitudes over 8,000 ft—and especially over 12,000 ft! Drink tons of water and consider bringing doctor-recommended medications that can alleviate symptoms. Acclimating at altitude for a few days before your wedding can also help. It is your responsibility to know your level of ability for hiking—especially at high altitudes. Consider planning a trip before your day so you can test your level of comfort with altitude.
Colorado has many amazing views that are up dirt roads. Some dirt roads are maintained and can be accessed carefully with 2WD cars, and some are so treacherous that only very experienced 4WD professionals with top-level off road vehicles are recommended to traverse them. Many dirt roads in CO are closed from October-May, and some don't open for the season due to snow until mid-June or July. In general, if you plan on going on any dirt roads in Colorado, or if you're traveling here between the months of October & May, a 4WD car can make the experience safer & more comfortable. Many dirt roads require 4WD vehicles, and some have chain laws depending on the season. Check CDOT for current road conditions, status updates, and closure information. And this website is a great resource on the level of difficulty of many of the dirt roads in Colorado. You can also search for the name of the road or location on youtube, and watch a first-hand video of what the road is like. Checking Instagram for recent photos of the road can give you an idea of snow levels. If the road is maintained by the forest service, calling the rangers directly is your best bet to get current & accurate information about a road's status.
Weather in the mountains can be very unpredictable. I have seen it be 45-degrees and snowing at 12,000 ft in the middle of July. Above treeline, on the high-alpine tundra, it's a completely different climate—and almost feels like a different world. Even if the forecast is 80 degrees in the nearest town, there can be a drop in temperature of 5-10 degrees per 1,000 ft of elevation gain—meaning it could be only 40-50 degrees on the mountain pass or at the top of a hike. Also, because of the lack of trees, the wind is usually much stronger above treeline, so windchill is a factor in temperature as well—so it's important to be prepared!