Women’s Merrell Thermo Chill Mid Winter Boot Review

Bottom Line

The Merrell Thermo Chill Mid winter boots come with many great features for winter hiking, such as excellent water resistance, adequate warmth, and a weight that makes walking in them nearly effortless. We tested these winter boots side-by-side with our other top selections to provide better insight into their performance and rank them.

We found that the Thermo Chill boots have numerous strengths and a few weaknesses to consider when deciding if they will be a good fit for your needs. One aspect we love about these boots is their impressive water resistance. This was somewhat surprising to us given the materials, but they remained dry for over two hours when fully submerged in several inches of water. This means they are an excellent choice for hiking on wet trails, as long as moisture doesn’t seep into the top of the boot.

They are also very lightweight compared to many of the women’s winter boots we tested; when we used them on local hikes in southwestern Colorado, they were effortless to walk in for miles at a time. One consideration is that these boots could potentially feel uncomfortable at the ankles for some individuals. It is wise to try them on or purchase them from a retailer that allows returns just to be safe. Overall, we really like these boots as they can be used year-round for hiking trails.

How We Tested

Our gear tester primarily used these boots on dry, chilly winter hikes in southwestern Colorado. The hikes were generally about five miles long and took place on rolling terrain. A few of the hikes included patches of ice and snow to navigate, while others featured rutted washouts that made the trail uneven in some areas.

Weight

The small size and simple design of the Thermo Chill boots result in a relatively lightweight. When we placed these boots on a kitchen scale, they weighed 15.8 ounces, or just under a pound. This makes them among the lightest boots we tested and the lightest hiking-specific boot in our lineup.

While hiking, it’s easy to feel the difference. Unlike some hiking boots, this model doesn’t feel like a brick on your feet. Instead, these boots feel like a blend of a more traditional boot and a trail runner. This design makes them easier and less tiring to wear, especially over longer distances.

Water Resistance

We were incredibly surprised at how water resistant these boots are; they stayed bone dry after over two hours of submersion. To better compare the boots in our lineup, we placed each model in a bathtub filled with several inches of water. Rocks were placed inside each model to prevent them from floating or flipping over. We made sure that the water reached the laces, as the tongue is a common leak point. Over the course of two hours, we checked inside the boots for moisture approximately every five minutes.

We fully expected these boots to wet out quickly since the materials do not seem particularly water-resistant. However, once submerged, it became clear that the boots have hydrophobic properties. The water pockets that formed on the outside of the boots made this apparent. After two hours in the water, we found no signs of moisture inside the boots.

For buyers, this means that these boots are an excellent choice for hiking in wet conditions. As long as moisture does not enter from the top of the boot, they should withstand water crossings, rain, and snow. They can also be easily paired with gaiters using the attachment ring below the laces to enhance their water resistance.

Warmth

The overall performance of the Merrell Thermo Chill in the warmth test was average, but its insulation level is adequate for hiking activities. To better compare the boots in our lineup, we placed each pair in a shaded snowdrift. We then used a laser thermometer to measure the temperature inside each boot every five minutes for half an hour. The lowest recorded temperature for the Thermo Chill boots was 32.7°F, which is about average compared to all the boots we tested.

This is not surprising since, although these boots have insulation, their lightweight design suggests that the insulation is not as thick as some others. This is not necessarily a drawback for a winter boot intended for hiking.

Given that hiking typically involves a fair amount of cardio, the feet tend to stay warmer than they would, for example, while strolling around a park or sitting outside at a festival. Our feet remained warm while using these boots in temperatures ranging from the 20s to the 40s, wearing just basic hiking socks.

Comfort

There are a moderate amount of adjustment features available for the Thermo Chill boots, but how they fit an individual’s ankles is the most significant factor for comfort. We didn’t find these boots particularly comfortable because the mid-rise tops rubbed against our ankles.

However, we acknowledge that the fit of these types of boots can often vary from person to person, and not everyone may have the same experience. For this reason, we placed more emphasis on sizing and adjustment options when ranking the boots we tested. These boots come in half sizes, which we appreciate, but there isn’t a wide variety in toe box sizing.

Like most boots in our lineup, the insole is removable, allowing for an orthotic insert to be added for increased comfort. The metal lace eyelet also enhances the adjustability of the overall fit. We also found the grid fleece on the upper ankle of the boot to be cozy, though not as warm as some of the wool and faux fur linings we have experienced. Overall, while our experience wearing these boots wasn’t the most comfortable, they are worth trying on.

Traction

The tread on the Merrell Thermo Chill Mids is fairly average for a hiking boot and is generally less aggressive than some of the other winter boots we tested. We developed a traction testing device that has a lever arm that increases the angle for a boot positioned on a rock. We used this to determine the angle at which each boot would lose traction with the ground.

During our tests, the Thermo Chill boots lost traction at a relatively low angle. This is understandable since, although there is decent tread, it is not significantly beefier than a summer hiking boot. While wearing these boots on hikes, we found they performed quite well on dry terrain.

Even when navigating steep slopes due to erosion or downhill trails, we never felt at risk of slipping and falling. However, we needed to be cautious in areas with patchy snow and ice. The boots managed well on snow, but we nearly slipped multiple times on the ice. We recognize that no boot can provide 100% traction on ice and that traction devices yield better results. Nonetheless, we believe that their overall performance was not as robust as some of the other boots we tested.

Should You Buy the Merrell Thermo Chill Mid?

The Thermo Chill Mid is ideal for hiking in wet and chilly conditions due to its impressive water resistance, lightweight design, and moderate insulation. While the shape, laces, and construction are not the most stylish nor the most practical for casual use, we found that the mid height makes them unsuitable for deep snow unless paired with gaiters.

We recommend trying them on or ordering from a retailer like REI that allows returns to ensure these boots fit your ankle shape for the best experience.

What Other Women’s Winter Boots Should You Consider?

There are so many different winter boots on the market, it can be challenging to find the best one for your needs. Fortunately, we have tested the best winter boots to help narrow things down. Here are a few of our other favorite hiking focused boots to consider:

Oboz Bridger 7” Insulated Review: As one of our favorite boots overall, we would be remiss if we didn’t mention the Bridger 7”. Like the Thermo Chill boots they are incredibly waterproof, though they do weigh a bit more. Their cozy lining and better insulation make them better for lower temperatures. While they are also intended for hiking, their design is a bit more suited for casual use.

Keen Revel IV Polar Review: The Keen Revel IV Polar boots are another of our favorite year-round options. These boots were quite comfortable to wear while backpacking in New Mexico and they have similar warmth to the Thermo Chill boots. Our biggest grievance is that the waterproofing could use some improvement.

Bogs Neo Classic Tall Review: The Bogs Neo Classic Tall boots are not hiking specific, but we still like to wear them on the trail for a variety of reasons. The first is that their taller height means they are better for deep powder, particularly because they are easier to take on and off. They have moderate insulation for cold days, but weigh a bit more due to their design.