Question 1

How many half marathons in Colorado are there in 2027?

Accepted Answer

There are 4 upcoming half marathons in Colorado listed on 42Cal, from April 2027 through June 2027. The count updates automatically as races are added.

Question 2

When is the best time for half marathons in Colorado?

Accepted Answer

Most of the 5 races on this list (3 of them) fall in April–May 2027.

Question 3

Which race in this list has the least elevation gain?

Accepted Answer

Colorado Marathon in Fort Collins is the flattest race on this list, with about 591 ft of total elevation gain — based on the 5 of 5 races here with elevation data on file.

Question 4

How current is this list?

Accepted Answer

This list was last refreshed on October 1, 2026. Race dates, locations, and course details are updated continuously as organizers confirm changes, so this page reflects the calendar as of that date.

Race	Date	Location	Distance	Elevation	Status
Horsetooth Half Marathon	April 2027	Fort Collins, United States	Half Marathon	280 m	Registration Open
Colorado Marathon	May 2027	Fort Collins, United States	Marathon	180 m	Registration Open
Colfax Marathon	May 2027	Denver, United States	Marathon	211 m	Opening Soon
Steamboat Marathon	June 2027	Steamboat Springs, United States	Marathon	736 ft	Registration Open
Boulderthon	September 2026	Boulder, United States	Marathon	603 ft	completed

Half Marathons in Colorado 2027

Upcoming Half Marathons in Colorado 2027

Horsetooth Half Marathon

Colorado Marathon

Colfax Marathon

Steamboat Marathon

Recently Run

Boulderthon

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