Organized by Troy’s California Trail Runs, the Winter edition is a compact, well-marked trail festival based inside Calero County Park that suits everyone from family-fun runners to ultra-trainers. Race day typically opens with a Kids Run at ~7:30 AM and the main distances starting around 8:00 AM, with aid stations, GPX/course maps and finish medals for entrants. Expect predominantly single-track and fire-road surfaces, challenging climbs/descents through oak groves, panoramic exposures and dirt-trail footing that make the 50K a popular Western-States-style training loop.
Races
50 km
Marathon
25 km
Half Marathon
15 km
10 km
5 km
Race Date:
06 December, 2025
The 50K Ultra is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park, San Jose, California. It is the toughest event of the day, featuring a demanding ultramarathon course through the park’s rolling hills.
Race Date:
06 December, 2025
Organized by Troy’s California Trail Runs, the Trail Marathon runs on December 6, 2025, at Calero County Park in San Jose, California. Participants complete a full marathon entirely on rugged trails with steep ascents and descents.
Race Date:
06 December, 2025
Also organized by Troy’s California Trail Runs, the 25K race takes place on December 6, 2025 at Calero County Park, San Jose, California, with the 13-mile plus 5K loop layout. The course has about 2,726 feet (~831 m) of elevation gain, offering a solid mid-to-long distance challenge.
Race Date:
06 December, 2025
The Half Marathon, hosted by Troy’s California Trail Runs, is also held on December 6, 2025 at Calero County Park, San Jose, California, starting at 8:00 AM. Runners will face ~ 2,477 feet (~755 m) of climb through challenging hills, dirt trails, and scenic exposure.
Race Date:
06 December, 2025
Organized by Troy’s California Trail Runs, the 15K takes place on December 6, 2025, at Calero County Park in San Jose, California. Runners tackle a longer loop with more climbs and rugged terrain.
Race Date:
06 December, 2025
Organized by Troy’s California Trail Runs, the 10K takes place on Saturday, December 6, 2025 at Calero County Park, San Jose, California, beginning at 8:00 AM. The course features ~ 1,187 feet (~362 m) of elevation gain, rolling through single-track and dirt paths with oak trees and panoramic views.
Race Date:
06 December, 2025
The 5K at the Calero Trail Run (Winter) is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park in San Jose, California. This short course provides a great introduction to trail running on scenic park paths.
Weather based on historical averages.
FAQs
What is the Calero Trail Run 50K?
How long is the Calero Trail Run 50K?
Where does the Calero Trail Run 50K take place?
What is the elevation gain of the Calero Trail Run 50K?
How can I prepare for the Calero Trail Run 50K?
How do I choose the right training plan for the Calero Trail Run 50K?
The 50K Ultra is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park, San Jose, California. It is the toughest event of the day, featuring a demanding ultramarathon course through the park’s rolling hills.
The Calero Trail Run 50K is 50km long.
The Calero Trail Run 50K takes place in San Jose, CA, USA.
The Calero Trail Run 50K elevation gain is 2093 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 50K?
The 50K Ultra is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park, San Jose, California. It is the toughest event of the day, featuring a demanding ultramarathon course through the park’s rolling hills.
How long is the Calero Trail Run 50K?
The Calero Trail Run 50K is 50km long.
Where does the Calero Trail Run 50K take place?
The Calero Trail Run 50K takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run 50K?
The Calero Trail Run 50K elevation gain is 2093 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run 50K?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run 50K?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run Marathon?
How long is the Calero Trail Run Marathon?
Where does the Calero Trail Run Marathon take place?
What is the elevation gain of the Calero Trail Run Marathon?
How can I prepare for the Calero Trail Run Marathon?
How do I choose the right training plan for the Calero Trail Run Marathon?
Organized by Troy’s California Trail Runs, the Trail Marathon runs on December 6, 2025, at Calero County Park in San Jose, California. Participants complete a full marathon entirely on rugged trails with steep ascents and descents.
The Calero Trail Run Marathon is 42km long.
The Calero Trail Run Marathon takes place in San Jose, CA, USA.
The Calero Trail Run Marathon elevation gain is 1748 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run Marathon?
Organized by Troy’s California Trail Runs, the Trail Marathon runs on December 6, 2025, at Calero County Park in San Jose, California. Participants complete a full marathon entirely on rugged trails with steep ascents and descents.
How long is the Calero Trail Run Marathon?
The Calero Trail Run Marathon is 42km long.
Where does the Calero Trail Run Marathon take place?
The Calero Trail Run Marathon takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run Marathon?
The Calero Trail Run Marathon elevation gain is 1748 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run Marathon?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run Marathon?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 25K?
How long is the Calero Trail Run 25K?
Where does the Calero Trail Run 25K take place?
What is the elevation gain of the Calero Trail Run 25K?
How can I prepare for the Calero Trail Run 25K?
How do I choose the right training plan for the Calero Trail Run 25K?
Also organized by Troy’s California Trail Runs, the 25K race takes place on December 6, 2025 at Calero County Park, San Jose, California, with the 13-mile plus 5K loop layout. The course has about 2,726 feet (~831 m) of elevation gain, offering a solid mid-to-long distance challenge.
The Calero Trail Run 25K is 25km long.
The Calero Trail Run 25K takes place in San Jose, CA, USA.
The Calero Trail Run 25K elevation gain is 831 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 25K?
Also organized by Troy’s California Trail Runs, the 25K race takes place on December 6, 2025 at Calero County Park, San Jose, California, with the 13-mile plus 5K loop layout. The course has about 2,726 feet (~831 m) of elevation gain, offering a solid mid-to-long distance challenge.
How long is the Calero Trail Run 25K?
The Calero Trail Run 25K is 25km long.
Where does the Calero Trail Run 25K take place?
The Calero Trail Run 25K takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run 25K?
The Calero Trail Run 25K elevation gain is 831 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run 25K?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run 25K?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run Half Marathon?
How long is the Calero Trail Run Half Marathon?
Where does the Calero Trail Run Half Marathon take place?
What is the elevation gain of the Calero Trail Run Half Marathon?
How can I prepare for the Calero Trail Run Half Marathon?
How do I choose the right training plan for the Calero Trail Run Half Marathon?
The Half Marathon, hosted by Troy’s California Trail Runs, is also held on December 6, 2025 at Calero County Park, San Jose, California, starting at 8:00 AM. Runners will face ~ 2,477 feet (~755 m) of climb through challenging hills, dirt trails, and scenic exposure.
The Calero Trail Run Half Marathon is 21km long.
The Calero Trail Run Half Marathon takes place in San Jose, CA, USA.
The Calero Trail Run Half Marathon elevation gain is 755 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run Half Marathon?
The Half Marathon, hosted by Troy’s California Trail Runs, is also held on December 6, 2025 at Calero County Park, San Jose, California, starting at 8:00 AM. Runners will face ~ 2,477 feet (~755 m) of climb through challenging hills, dirt trails, and scenic exposure.
How long is the Calero Trail Run Half Marathon?
The Calero Trail Run Half Marathon is 21km long.
Where does the Calero Trail Run Half Marathon take place?
The Calero Trail Run Half Marathon takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run Half Marathon?
The Calero Trail Run Half Marathon elevation gain is 755 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run Half Marathon?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run Half Marathon?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 15K?
How long is the Calero Trail Run 15K?
Where does the Calero Trail Run 15K take place?
What is the elevation gain of the Calero Trail Run 15K?
How can I prepare for the Calero Trail Run 15K?
How do I choose the right training plan for the Calero Trail Run 15K?
Organized by Troy’s California Trail Runs, the 15K takes place on December 6, 2025, at Calero County Park in San Jose, California. Runners tackle a longer loop with more climbs and rugged terrain.
The Calero Trail Run 15K is 15km long.
The Calero Trail Run 15K takes place in San Jose, CA, USA.
The Calero Trail Run 15K elevation gain is 534 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 15K?
Organized by Troy’s California Trail Runs, the 15K takes place on December 6, 2025, at Calero County Park in San Jose, California. Runners tackle a longer loop with more climbs and rugged terrain.
How long is the Calero Trail Run 15K?
The Calero Trail Run 15K is 15km long.
Where does the Calero Trail Run 15K take place?
The Calero Trail Run 15K takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run 15K?
The Calero Trail Run 15K elevation gain is 534 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run 15K?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run 15K?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 10K?
How long is the Calero Trail Run 10K?
Where does the Calero Trail Run 10K take place?
What is the elevation gain of the Calero Trail Run 10K?
How can I prepare for the Calero Trail Run 10K?
How do I choose the right training plan for the Calero Trail Run 10K?
Organized by Troy’s California Trail Runs, the 10K takes place on Saturday, December 6, 2025 at Calero County Park, San Jose, California, beginning at 8:00 AM. The course features ~ 1,187 feet (~362 m) of elevation gain, rolling through single-track and dirt paths with oak trees and panoramic views.
The Calero Trail Run 10K is 10km long.
The Calero Trail Run 10K takes place in San Jose, CA, USA.
The Calero Trail Run 10K elevation gain is 362 metres, which Runna classifies as a Hilly race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 10K?
Organized by Troy’s California Trail Runs, the 10K takes place on Saturday, December 6, 2025 at Calero County Park, San Jose, California, beginning at 8:00 AM. The course features ~ 1,187 feet (~362 m) of elevation gain, rolling through single-track and dirt paths with oak trees and panoramic views.
How long is the Calero Trail Run 10K?
The Calero Trail Run 10K is 10km long.
Where does the Calero Trail Run 10K take place?
The Calero Trail Run 10K takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run 10K?
The Calero Trail Run 10K elevation gain is 362 metres, which Runna classifies as a Hilly race.
How can I prepare for the Calero Trail Run 10K?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run 10K?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 5K?
How long is the Calero Trail Run 5K?
Where does the Calero Trail Run 5K take place?
What is the elevation gain of the Calero Trail Run 5K?
How can I prepare for the Calero Trail Run 5K?
How do I choose the right training plan for the Calero Trail Run 5K?
The 5K at the Calero Trail Run (Winter) is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park in San Jose, California. This short course provides a great introduction to trail running on scenic park paths.
The Calero Trail Run 5K is 5km long.
The Calero Trail Run 5K takes place in San Jose, CA, USA.
The Calero Trail Run 5K elevation gain is 77 metres, which Runna classifies as a Moderate race.
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
What is the Calero Trail Run 5K?
The 5K at the Calero Trail Run (Winter) is organized by Troy’s California Trail Runs on Saturday, December 6, 2025, at Calero County Park in San Jose, California. This short course provides a great introduction to trail running on scenic park paths.
How long is the Calero Trail Run 5K?
The Calero Trail Run 5K is 5km long.
Where does the Calero Trail Run 5K take place?
The Calero Trail Run 5K takes place in San Jose, CA, USA.
What is the elevation gain of the Calero Trail Run 5K?
The Calero Trail Run 5K elevation gain is 77 metres, which Runna classifies as a Moderate race.
How can I prepare for the Calero Trail Run 5K?
The best way to train for the next race is to use a personalised training plan that takes into account your current running ability, schedule, and preferences.
This will help you steadily improve your running performance and get ready for the race without risking an injury.
Check out our training plans to find the best running program for your goals!
How do I choose the right training plan for the Calero Trail Run 5K?
Which plan you choose will depend on your experience, schedule, objectives, and the date of the race.
Runna offers personalised training plans for every runner and every goal: Whether this is your first, 10th or 100th race, we'll help you get the most out of your training and smash your goals.
Check out our training plans to find the best running program for your goals!
More
Sport:
Running
Tags:
Nature
Kid friendly
Park
This event listing is for informational purposes only. Runna is not affiliated with, endorsed by, or sponsored by Calero Trail Run (Winter) or Troy’s California Trail Runs. All event details are based on publicly available information and are provided solely to help users discover running events. Runna does not use any official logos, images, or proprietary content from this event or its organiser. Any trademarks or names mentioned are used descriptively to identify the event in a factual manner. For the most accurate and up to date information (including to register or purchase an entry to the event), please visit the Calero Trail Run (Winter) website.
