Winter work is hard on a crew in ways summer work isn't. Fingers go numb and drop tools. Boots slide on a frosted deck. Someone who started the morning shivering stops shivering by lunch, and that's a bad sign, not a good one.
This guide covers what cold stress is, how wind chill changes the risk, the warning signs to watch for, and the cold weather PPE that keeps people working safely, including Ergodyne N-Ferno balaclavas and warmers and Ergodyne TREX ice cleats.
Shop Ergodyne Cold Weather GearWhat Is Cold Stress?
Cold stress happens when your body loses heat faster than it can make it. Skin temperature drops first, then your core temperature. Wind, wet clothing, and contact with cold surfaces like steel, concrete, or frozen ground all speed that up.
Anyone working outdoors in winter is exposed: framers, roofers, ironworkers, road crews, utility linemen, and anyone running equipment. So are people working in freezers or unheated warehouses. Workers who are wet, worn out, new to the cold, or who have conditions like diabetes or high blood pressure are at higher risk.
Wind Chill: Why the Thermometer Lies
Air temperature only tells half the story. Wind strips away the thin layer of warm air around your body, so exposed skin loses heat much faster. That's what the wind chill number measures. On a 20°F morning with a 15 mph wind, exposed skin cools as if it were 6°F. At 0°F with the same wind, it feels like −19°F.
| Wind | 40°F | 30°F | 20°F | 10°F | 0°F | -10°F |
|---|---|---|---|---|---|---|
| 5 mph | 36° | 25° | 13° | 1° | -11° | -22° |
| 10 mph | 34° | 21° | 9° | -4° | -16° | -28° |
| 15 mph | 32° | 19° | 6° | -7° | -19° | -32° |
| 20 mph | 30° | 17° | 4° | -9° | -22° | -35° |
| 30 mph | 28° | 15° | 1° | -12° | -26° | -39° |
| 40 mph | 27° | 13° | -1° | -15° | -29° | -43° |
Calculated with the National Weather Service wind chill formula. Darker cells mean faster heat loss from exposed skin. See the full NWS wind chill chart for frostbite times.
Check the forecast wind chill, not just the high temperature, when you plan outdoor work. Also remember that working at height, near open water, or on a moving vehicle or lift often means more wind than ground level.
Cold Stress Warning Signs
The early signs of cold stress are easy to brush off as part of a normal winter day. Teach your crew to recognize them in themselves and in each other.
| Condition | Warning signs | What to do |
|---|---|---|
|
Hypothermia Core body temperature drops below 95°F |
Shivering, fatigue, loss of coordination, confusion. In severe cases shivering stops, skin turns blue, and breathing slows. | Call 911 for severe symptoms. Move the worker somewhere warm and dry, remove wet clothing, and warm the center of the body first. Warm, non-alcoholic drinks only if they are alert. |
|
Frostbite Skin and tissue freeze |
Numbness, reddened skin that develops gray or white patches, skin that feels firm or hard. Usually fingers, toes, nose, ears, and cheeks. | Get to a warm area and get medical help. Don't rub the area, and don't break blisters. Loosely cover the affected skin. |
|
Trench foot Non-freezing injury from wet, cold feet |
Red skin, numbness, swelling, leg cramps, tingling pain, blisters. It can happen at temperatures as high as 60°F if feet stay wet. | Remove wet boots and socks, dry the feet, avoid walking on them, and get medical attention. |
|
Chilblains Small blood vessels damaged by repeated cold |
Redness, itching, blisters, and inflammation, often on fingers, toes, ears, and cheeks. | Warm the skin slowly, don't scratch, and keep blisters clean and covered. |
Based on the OSHA Cold Stress Guide. This is general safety information, not medical advice. When in doubt, call 911.
How to Layer for Cold Weather Work
The best cold weather clothing system isn't one heavy coat. It's several thinner layers you can adjust as the day warms up or your work gets more physical. Sweat is the enemy: once your base layer gets damp, it pulls heat out of you all day.
Base layer
Pulls sweat away from your skin so you stay dry.
Look for: synthetic or wool knit. Skip cotton, which holds moisture and loses its warmth when wet.
Insulating layer
Traps warm air. Add or remove it as your activity level changes.
Look for: fleece, wool, or a lightly insulated jacket or vest.
Outer shell
Blocks wind and wet. On roads and active sites, it should also be hi-vis.
Look for: wind and water resistance, room to move, and reflective trim.
Don't forget Head, face, hands, and feet lose heat fastest. Cover them separately.
Keep layers loose enough that they don't restrict blood flow, especially at the wrists and ankles. On roads and active sites, the outer layer should keep you visible. Ergodyne's GloWear hi-vis apparel includes hi-vis outerwear made for that.
Head, Face, and Neck Protection
Your head, face, and neck are often the most exposed skin on a jobsite, and a hard hat on its own does nothing to keep them warm. A thin balaclava, stretch cap, or hard hat liner fills that gap.
- Balaclavas cover the head, ears, neck, and most of the face, leaving an opening for the eyes, nose, and mouth. The N-Ferno 6821 Fleece Balaclava is a thin fleece option with reflective accents that fits under a hard hat.
- Stretch caps are lighter, close-fitting knit hoods. The N-Ferno 6815 Full-Face Stretch Cap covers the ears and lower face and is made to be worn with a hard hat.
- Neck gaiters seal the gap between collar and chin, and you can pull them up over your nose in high wind. The N-Ferno 6961 Reflective Winter Neck Gaiter adds reflective trim for low-light work.
- Hard hat winter liners attach to the hard hat itself. Browse Ergodyne thermal liners for options.
Whatever goes under your hard hat, make sure the hat still sits level and the suspension can be adjusted to fit. Follow the hard hat manufacturer's guidance on approved liners.
Hand, Foot, and Body Warmers
Hands and feet are the first places the body cuts blood flow when it gets cold, which is why fingers and toes go numb first. Numb fingers drop tools and fumble fasteners. Insulated gloves are the first fix. Our work glove guide covers what to look for. On the coldest days, warmers fill the gap.
Ergodyne N-Ferno warmers are air-activated: open the package and they start heating on their own, with no batteries or charging.
- N-Ferno 6990 Hand Warming Packs: slip one into each glove or pocket. Ergodyne lists up to 12 hours of heat.
- N-Ferno 6995 Insole Foot Warmers: full-foot warmers with an adhesive back that sticks to your socks, thin enough for work boots. They last up to 8 hours.
- N-Ferno 6997 Body Warmers: larger packs you can place over a base layer on your lower back or core for targeted warmth.
Follow the directions on each package. Don't put warmers directly against bare skin, and check skin regularly. Anyone with poor circulation or diabetes should be especially careful, because they may not feel a warmer getting too hot.
Ice Cleats and Slip Prevention
Slips and falls on ice and snow are some of the most common winter injuries on any jobsite. Ice cleats add metal studs under your boots for grip on packed snow and ice: parking lots, ramps, trailer steps, and frozen ground.
Full-coverage traction
Mid-sole cleats
- Strap under the arch of the boot.
- Rotate to the top or side when you go indoors.
- Choose TREX 16320 for flat-soled footwear or TREX 16321 for boots with a defined heel.
Size full-coverage cleats to your boot, not your shoe size, because work boots run larger. TREX 6300 comes in Medium through 2XL. Take cleats off or rotate them out of the way before you climb a ladder or walk on smooth indoor floors.
A Cold Weather Plan for Your Crew
OSHA doesn't have a standard written specifically for cold weather work, but employers are still expected to protect workers from recognized hazards, and cold stress is one of them. The OSHA Cold Stress Guide recommends a few practical controls:
- Schedule around the cold. Do the coldest, most exposed tasks during the warmest part of the day when you can.
- Provide warm breaks. Give crews a heated space to warm up and dry off, and take more frequent short breaks on the coldest days.
- Use the buddy system. Pair workers up so someone notices when a coworker starts showing signs of cold stress.
- Train everyone. Make sure every worker knows the warning signs in the table above and what to do about them.
- Keep spares on site. Extra dry socks, gloves, liners, and warmers should be in the truck or job box.
- Ease new workers in. People new to the cold, or coming back after time off, need time to adjust.
- Watch for dropped tools. Bulky gloves and numb hands make drops more likely. Our Ergodyne tool tethering guide covers how to keep tools from falling.
Key Takeaways
- Cold stress includes hypothermia, frostbite, trench foot, and chilblains. Trench foot can happen well above freezing when feet stay wet.
- Plan around wind chill, not air temperature. 20°F with a 15 mph wind feels like 6°F on exposed skin.
- Layer for warmth and dryness: base layer, insulating layer, outer shell.
- Cover the head, face, and neck under the hard hat with a balaclava, stretch cap, or liner.
- Air-activated warmers and ice cleats handle the coldest and slickest days.
Frequently Asked Questions
What is cold stress?
Cold stress happens when cold temperatures, wind, or wet conditions pull heat from your body faster than it can make it. Skin temperature drops first, then core body temperature. The main cold stress injuries are hypothermia, frostbite, trench foot, and chilblains.
At what temperature is it too cold to work outside?
OSHA has no specific temperature limit for outdoor work, but employers are expected to protect workers from recognized cold hazards. Wind chill matters more than air temperature alone: 20°F with a 15 mph wind feels like 6°F on exposed skin. Wet clothing makes any temperature more dangerous.
Does OSHA have a cold stress standard?
No. There is no OSHA standard written specifically for cold environments. Under the General Duty Clause, employers must still keep the workplace free of recognized hazards, which includes cold stress. OSHA's Cold Stress Guide lays out recommended controls such as training, warm breaks, and proper clothing.
Can you wear a balaclava under a hard hat?
Yes. Thin balaclavas and stretch caps, like the Ergodyne N-Ferno 6821 and 6815, are made to be worn under a hard hat. Make sure the hard hat still sits correctly and the suspension can be adjusted to fit, and follow the hard hat manufacturer's guidance on what can be worn underneath.
How long do hand and foot warmers last?
It depends on the product. Ergodyne lists up to 12 hours of heat for the N-Ferno 6990 hand warming packs and up to 8 hours for the N-Ferno 6995 insole foot warmers. Both are air-activated, so they start warming once you open the package.
Are ice cleats safe to wear indoors?
Studded cleats can be slippery on smooth indoor floors and can scratch them, so take full-coverage cleats off before you go inside or climb a ladder. Ergodyne TREX mid-sole cleats are designed to rotate up to the top or side of the boot when you move indoors.
Can trench foot happen above freezing?
Yes. Trench foot is a non-freezing injury caused by feet staying cold and wet. According to OSHA it can happen at temperatures as high as 60°F if your feet are constantly wet. Change into dry socks and keep boots as dry as you can.
What should workers wear for cold weather work?
Dress in three layers: a moisture-wicking base layer, an insulating middle layer, and a wind- and water-resistant outer shell. Add a balaclava or liner under the hard hat, insulated gloves, warm waterproof boots, and a spare set of dry socks and gloves.