The Colorado Mountain Half+ Series 2026 returns to Littleton, Colorado on September 13th... The race offers a challenging half marathon through some of the state's most scenic landscapes, including Estes Park and Georgetown. Race morning in Littleton finds runners gathering at dawn. Temperatures hover around 18°C with slight wind speeds, creating an invigorating but comfortable start to the day. As participants make their way from the starting line on a well-marked trail, they are greeted by stunning views of the Rocky Mountains, setting a tone of adventure and exploration for those who sign up. This series is more than just races; it's about running among some of Colorado’s most beloved peaks. The half marathon spans 21 kilometers over terrain that transitions from firm to slightly soft underfoot, presenting both challenges and beauty along the way. Notable features include climbs and descents that test endurance and reward with breathtaking vistas. The race begins in Littleton near downtown at 7:00 AM on September 13th... Runners will navigate through varied landscapes typical of Colorado's trails—firm yet slightly soft surfaces, ensuring a balanced workout while enjoying the natural beauty. The course is set to provide runners with elevation changes and aid stations positioned strategically along the route for hydration and support. Weather conditions are forecasted to be mild with temperatures ranging from 10°C in the early morning up to 27°C as the day progresses... A moderate UV index indicates a need for sun protection but also allows for comfortable running. Precipitation is minimal, expected at just over one millimeter of rain, making it an ideal race-day condition.
5-Event Series 21km • Start: 07:00:00 • Fee: $440.65
Series 3 Pack 21km • Start: 07:00:00 • Fee: $274.81
Series 4 Pack 21km • Start: 07:00:00 • Fee: $360.41
Registration can be done through the official website: https://raceroster.com/events/2026/114192/colorado-mountain-half-series-2026... Fees for participation are $440.65 for the full series, $274.81 for a three-event pack, and $360.41 for four events. Bibs can be picked up at Littleton Community Center on September 9th from 1:00 PM to 7:00 PM... Participants should bring valid IDs and race bibs with them. The start line is located just off Main Street in downtown Littleton, near the intersection of Oak St. The event caters to runners aged 14 years old and above—first-timers are welcome but encouraged to check age requirements on registration information. For those who participate in this series, it's not only a race; it’s an opportunity to run among some of Colorado’s most beautiful landscapes while supporting local youth programs. The cause is meaningful as every mile runs contributes directly towards strengthening our communities and the next generation.
Races Offered
5-Event Series
Sep 13, 2026
straighten
Distance —
21km
terrain
Type —
Running
timer
07:00
sell
$440.65
Series 3 Pack
Sep 13, 2026
straighten
Distance —
21km
terrain
Type —
Running
timer
07:00
sell
$274.81
Series 4 Pack
Sep 13, 2026
straighten
Distance —
21km
terrain
Type —
Running
timer
07:00
sell
$360.41
Weather History
These values represent the 3-year monthly averages for September in Littleton.
thermostatTemperature
10.4° / 27.3°
wb_sunnyFeels like
7.9° / 24.0°
light_mode
Avg sunshine hours
11h 2m
water_drop
Avg rainfall
1.3 mm
ac_unit
Avg snowfall
—
air
Avg wind speed
7.8 km/h (Light breeze)
opacity
Sweat loss rate
Moderate
terrain
Course conditions
Firm and slightly soft
sunny
Max UV Index
Moderate (5.0)
humidity_mid
Humidity
47.3%
wb_twilight
Sunrise
06:41
nightlight
Sunset
19:06
About Littleton
Learn more about the host city, Littleton.
Littleton is a city of about 45,000 in the Denver Metropolitan Area of the western U.S. state of Colorado. The seat of Arapahoe County and also extending into adjacent Arapahoe and Douglas counties, the city lies south of Denver along the South Platte River. A former farming community, Littleton is now a residential suburb of Denver.