If you're looking for a sunny hike in the fall, I like Centennial Cone Park's upper loop. The trails wind through wide-open, rolling fields with few trees, so it's very sunny here.
The upper loop is about 12 miles, so I suggest picking a section at a time. The Elk Range Trail is a nice 6.4 mile out-and-back hike that can be started at the Camino Perdido trailhead or the Centennial Cone Road trailhead. You can easily turn around sooner for a shorter hike or continue further on the loop for a longer hike.
I recommend starting at the Centennial Cone Road trailhead (address below), otherwise you'll be doing quite a bit of elevation gain at the end on the return trip. However, expect ups and downs in both directions because of the rolling terrain.
At the trailhead you'll find a parking lot, bathrooms and a trail sign with maps.The trail is the wide, dirt road heading northeast out of the parking lot. Walk a couple hundred feet and you'll come to a trail split. Hikers wanting to do the full loop will turn right here for the Travois Trail. For this hike, continue on the wide road for the Elk Range Trail.
The trail is called the Elk Range Trail because it is an elk range. The entire park is closed each year from December 1-January 31 for elk and deer hunting. This trail remains closed from January 31 to approximately June 15 to protect the elk herd’s winter range and calving grounds from visitors, according to the Centennial Cone website.
The trail winds through the rolling hills, passing through some forested areas. However, the trees are not thick here and there is not much shade, so I would not visit on a warm, summer day. It's a great place to visit on a cool, fall day when you want the sun to warm you up as you hike.
If you hike here on a weekend, you will not see cyclists. That's because the park is hiker-only on odd numbered days, biker-only on even numbered days. With few people making the trek here and no cyclists on hiker days, the park is quite quiet.
About half-way along the trail, 1.5 miles from the trailhead, you'll come to a gate. Make sure you do a 360 degree turn here and enjoy the views around you. Pass through the gate, leaving it closed behind you. From this point on the trail, the trees disappear from around the trail. A short distance later, the road passes next to an old farm. It appears to still be a working cattle ranch, we saw several cows in the area. Make sure you check out the old windmill, but don't leave the trail or disturb anyone living here.
Near the farm, you'll pass through another gate. Again, leave it closed behind you. This is a great spot to turn around for a hike of about 3.7 miles RT. Otherwise, continue on the road, enjoying the views until you reach a nice bench at the next parking lot. Just before the parking lot (and bench), is another trail split. You can turn here and hike on the Travois Trail for as far as you like, or turn around here.
Details: An out-and-back hike on the Elk Range Trail is 6.4 miles RT with 1,000 feet of elevation gain with all the ups and downs. The trailhead is at 7,662 feet elevation. The high spot is at about 7,935.
Locations/Directions: Jefferson County Open Space suggests using the address 2234 Douglas Mountain Road for directions.
Park website with maps: http://jeffco.us/parks/parks-and-trails/centennial-cone-park/