News Flash

Parks Placeholder

Posted on: January 29, 2024

Freeze-Thaw Cycle

Freeze-Thaw Cycle

It’s a beautiful winter day, and you decide to load up the bike for a ride at your favorite St. Charles County park. However, after doing a little research, you discover all the natural surface trails are closed. Have you ever wondered why trails might be closed in winter when it hasn’t rained or snowed for days? It's likely because of the freeze-thaw cycle!

As the temperature drops, moisture in the soil freezes and expands the composition of the soil. The colder it gets, the thickness of the frozen dirt increases, resulting in a solid trail tread to ride. The trouble begins when the air temperature starts to rise to near or above 32 degrees, especially on sunny days. This is when the frozen water in the expanded soil begins to melt from the top down, and the trails become slick. As the ice continues to melt at the top, it has nowhere to go because the soil below is still frozen solid, resulting in a sloppy, slushy mess! This can be very destructive to a trail system, resulting in deep ruts that can harden to the point of being almost impossible to fix, and difficult or dangerous for others to use. Damaged trails must then be chopped up, reshaped, smoothed and compressed all over again. Volunteers spend hours reworking a trail they have already dedicated a significant amount of time building. 

Several factors determine whether a trail is in the freeze or thaw process, including soil composition, temperature and sun exposure. In Missouri, during the winter months, it’s common for trails to be rock solid first thing in the morning only to turn to mush in a very short time within the same day. If you choose to hike or ride during this time, it’s best to get an early start. Not all freeze/thaw scenarios are black and white. As an example, if the ground has been frozen solid for several days, the above-freezing air temperature on a cloudy day for a couple hours might just allow the trail tread to remain solid. Just the opposite, when the air temperature is above freezing most of the day and drops below freezing for a couple of hours overnight, ground temperatures will most likely stay above freezing because dirt is a good insulator. Snow also has an impact on the trail status as it is an insulator that either protects warmer soil from freezing temps or protects frozen soil from warmer air temps.

Does all this dirt science seem a bit confusing and more information than you want to process, just to decide whether the trails are suitable for a winter outing? The main thing to remember is if you see the trail tread starting to get soft, resulting in deep ruts and/or mud sticking to your tires, shoes, or horse hooves, make the right choice and get off the natural surface trails. You can also check the St. Charles County Parks Rainout Line to confirm trail conditions as well as the status of other park amenities

Facebook Twitter Email

Other News in Parks Placeholder

St. Charles County Parks - Park Activity Guide - Winter/Spring 2024

Park Activity Guide - Winter/Spring 2024

Posted on: November 30, 2023
Volunteer in the Parks

Volunteer in the Parks

Posted on: November 9, 2023
Bride and groom kissing at Klondike Park.

Host Your Special Occasion

Posted on: April 15, 2023
St. Charles County Kinetic Park

Kinetic Park Closures

Posted on: May 19, 2023