Like any trail, conditions in Rocky Mountain National Park can vary depending on time of year and weather. Not all hazardous trail conditions have to derail your hiking plans, but you might need special gear, depending on what's going on with the trail you want to hike.
The main natural causes of dangerous trail conditions are:
Fallen trees: These can make a trail impassable, but if the downed trees aren't too big you can sometimes scramble over them.
Ice: If you're going to hike an icy trail, it's a good idea to bring traction devices, usually some kind of chain that straps to your shoe, to help you walk on slippery terrain.
Snow: If there's just a bit of snow, waterproof hiking boots and maybe a traction device can do the trick. For areas with a lot of snow, you might consider snow shoeing! Pick up a pair of snow shoes and telescoping poles to help you keep your balance, and you can head out on even a snowy trail [source: Backpacking.net].
You might think of snow and ice as winter hiking conditions, but because of the elevation some trails in Rocky Mountain National Park have snow year-round, and conditions at this altitude can change quickly. It's a good idea to check trail conditions to make sure you have the right gear. Hiking in the snow without waterproof boots, for example, is uncomfortable at best and can be dangerous at worst. No matter when you're hiking or what the trail conditions, rain gear is a must. You don't want a surprise shower upping your risk for hypothermia.
Looking for information on trail conditions? The National Park Service maintains a list of user-submitted trail conditions, where hikers and volunteers fresh off of the trail can give current information about downed trees, icy trails, snowy conditions, and other possible trail hazards.