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Merrell Thermo Chill Mid WP - Women's Review

This well-priced boot hits all the marks with a winter-friendly design that maintains great traction, weatherproofing, and warmth
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Merrell Thermo Chill Mid WP - Women's Review (We brought the Thermo Chill Mid with us on winter camping adventures and they proved to be one of our preferred...)
We brought the Thermo Chill Mid with us on winter camping adventures and they proved to be one of our preferred choices for local trail hikes.
Credit: Liz Chamberlain
Price:  $130 List
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Manufacturer:   Merrell
By Liz Chamberlain ⋅ Review Editor  ⋅  Feb 23, 2022
81
OVERALL
SCORE
  • Warmth - 25% 8.0
  • Weather Protection - 25% 7.0
  • Comfort and Fit - 20% 9.0
  • Traction - 15% 9.0
  • Durability - 15% 8.0

Our Verdict

The Merrell Thermo Chill Mid is a fantastic boot thanks to its low price point and exceptional all-around performance. Through river-dips and choppy trail hikes, it was a stand-out boot for outdoor pursuits and everyday errands. The 6-inch collar height caused it to score lower in our weather protection metric, but the level of warmth, comfort, and versatility is still undeniable. While not be the most stylish boot in our lineup, the Thermo Chill is practical, functional, and almost too warm. If you're a winter outdoorswoman that's always on the move, this excellently-priced boot is a solid choice.
REASONS TO BUY
Good value
Ultra warm
Great traction
Highly waterproof
REASONS TO AVOID
Only ankle-high coverage
Hiking-specific style
Narrow fit
Editor's Note: We updated this boot review with new information to help you make a buying decision. This update occurred on February 23, 2022.

Our Analysis and Test Results

Throughout our tests of hiking-focused winter boots, we found the Thermo Chill to be one of the most reliable boots in terms of traction and mobility. The outsole provides a sticky and sturdy base to grip uneven surfaces, whether on ice or snow. The 200 grams of Merrell Select Warm insulation bring incredible warmth to high alpine adventures, and the fit is snug enough to feel confident on steep inclines. That said, the fit is a bit too narrow for those with wide feet, and the insulation is almost too warm on warmer winter days. Otherwise, we were thrilled with the performance of this boot, all at a more-than-fair price point.

Performance Comparison


merrell thermo chill mid wp for women - the pu-coated leather and mesh exterior proved to be durable...
The PU-coated leather and mesh exterior proved to be durable, waterproof, and quite abrasion resistant.
Credit: Liz Chamberlain


Warmth


The warmest options in our lineup all had roughly 200 grams of insulation, including this one. Merrell uses their proprietary insulation to bring excellent and reliable warmth to the Thermo Chill. Happily, this boot also has an impressive level of breathability, even when involved in sweaty situations with high moisture output. We did fall victim to swampy socks during a 50-degree day hike, but that seemed to be the exception.

During our ice bath tests, the Thermo Chill Mid had one of the lowest changes in temperature at -5.2°F. This means the boot has a high heat retention rate under exposure to cold temperatures. We wish the boot covered the skin above the ankle to increase this warmth retention but found that a thick tall sock did the job without limiting flexibility.

merrell thermo chill mid wp for women - the 200g of merrell select warm insulation makes for a surprisingly...
The 200g of Merrell Select Warm insulation makes for a surprisingly thin and lightweight internal lining that's still very warm.
Credit: Liz Chamberlain

Weather Protection


The Thermo Chill Mid is noticeably designed to withstand the elements. The PU-coated leather and mesh exterior makes for a thick-yet-breathable barrier that kept our feet dry from water and snow throughout all our field tests. Hiking boots are designed with movement in mind, so when you factor mobility into the design, the boot height needs to be low enough to bend and flex the ankle. This lower height does, however, mean that the boot offers a bit less inherent weather protection than a taller boot. That said, gaiters are always a compatible option.

Again, a lower shaft and collar height means less coverage during deeper snow days. For some, this can be less than ideal. If you're a well-seasoned winter hiker, you're likely okay with wearing a thick pair of socks or strapping on a gaiter. Unfortunately, small amounts of snow stuffed into the boot's collar without a gaiter, but thankfully no snow seeped into the interior. We were most impressed with these boots' ability to keep water out. We submerged our feet in our local river for over 3 minutes, up to just an inch below the top of the boot, and experienced no water leakage. While this is only 5 inches of water resistance, that's likely all you need for typical weather.

merrell thermo chill mid wp for women - we took the thermo chill down to the river to test waterproofness...
We took the Thermo Chill down to the river to test waterproofness. They were impressively waterproof all the way to about an inch below the collar.
Credit: Liz Chamberlain

Comfort and Fit


The Thermo Chill Mid gave us one of our favorite fits of all our tested boots. It is one of the more snug boots and has a super comfortable lining. That said, while our narrow-footed testers loved the fit, it was too tight for wider feet, mainly through the instep and toe box. Even our testers with narrow feet agreed that the boot feels somewhat tight with thick socks on.

Mobility is a huge factor in the comfort equation and a large part of why the Thermo Chill Mid scored so well here. We felt like we could run, jump, and skip on trails or simply walk around in it for an entire workday in this boot. The midsole structure paired with the Kinetic Fit Base footbed provides excellent arch support.

The shape of the Thermo Chill Mid is on the narrow side, which may...
The shape of the Thermo Chill Mid is on the narrow side, which may be a bit too slim for wide-footed females.
The Kinetic Fit Base footbed is quite thin but boasts small holes in...
The Kinetic Fit Base footbed is quite thin but boasts small holes in the forefoot to enhance breathability.

Traction


We were very impressed with the traction capabilities of the Thermo Chill Mid. The 5mm lug depth provides great traction on inclines, and the grippy wave pattern at the toe and heel creates a smooth transfer of balance on trails.

Despite the excellent traction we experienced during our testing period, the rubber on the outsole of the Thermo Chill is a bit softer than some of the other outsole compounds in our lineup. The drawback with soft rubber is its sticky nature on warmer surfaces and its quicker wear rate. Depending on your intended use for this boot, you could still get multiple seasons out of the soft rubber so long as it's used in primarily cold, wintery conditions. Bottom line, this is an all-around exceptional and versatile boot for everything from outdoor work to winter adventures to walks through the ski resort.

The outsole on the Thermo Chill Mid has an interesting pattern with...
The outsole on the Thermo Chill Mid has an interesting pattern with toe and heel waves that spread for uphill traction, and thick lugs beneath for lateral traction.
The Merrell Select Grip outsole pattern proved to be super grippy on...
The Merrell Select Grip outsole pattern proved to be super grippy on wet and slippery snow.

Durability


The Thermo Chill has PU-coated leather, which is far more waterproof than untreated leather, allowing it to withstand frequent exposure to moist environments. This boot also has deep lugs on the outsole made from a slightly softer rubber compound. This can wear more quickly on pavement and warmer surfaces but has a relatively long lifespan when used on colder surfaces.

Merrell's in-house M Select Dry permeable membrane increases the upper's breathability and helps extend the lifespan by increasing air and moisture flow. This may not be as obvious a part of durability. Still, the happier your feet remain through changing temperatures and moisture levels, the less overall strain is put on the materials of your boot.

merrell thermo chill mid wp for women - the merrell thermo chill was kept in our truck all season long. it...
The Merrell Thermo Chill was kept in our truck all season long. It one of the most toasty, practical, and functional footwear in the lineup at a fair cost.
Credit: Liz Chamberlain

Should You Buy the Merrell Thermo Chill Mid WP?


The Thermo Chill is a high-value, durable, and reliable winter boot. Despite a lack of style for everyday use, it is incredibly functional and therefore versatile for most activities. For those in need of comfort and support, this affordable boot will give you what you need. Wear it on the way to your local ski resort or a Sunday morning dog walk. We approve. This boot has one of the lowest price points in the group yet is one of the shining stars for warmth, comfort, traction, and protection.

What Other Winter Boots Should You Consider?


A slightly taller hiker we like is the Keen Revel IV Polar. With a somewhat higher price, this boot might be more appropriate for deeper snow or activities like snowshoeing. It offers similar warmth, weather protection, and traction to the Merrell. Alternatively, if you want a more all-around boot, the UGG Adirondack III is one to consider with impressive performance across the board, it is hard to do better, but the price is higher.

Liz Chamberlain