For many Kenyans, the first serious encounter with extreme cold happens in two very different settings: on the upper slopes of Mount Kenya or Mount Kilimanjaro, or thousands of kilometres away in wintertime Europe, United States, or Canada. In both cases, one item quietly determines whether the experience is memorable or miserable: the thermal suit, commonly known as long johns.
Thermal suits are base layers—worn closest to the skin—designed to regulate body temperature, manage moisture, and keep you warm without restricting movement. Understanding how to choose the right one is essential for safety, comfort, and performance.
Why Thermal Suits Matter in High-Altitude and Winter Conditions
1. Cold at Altitude is Different
On Mount Kenya and Kilimanjaro, temperatures can drop well below freezing near the summit, especially before dawn. Wind chill amplifies the cold, and fatigue reduces your body’s ability to generate heat. A good thermal suit traps warmth while allowing sweat to escape, preventing the dangerous cycle of sweating, chilling, and heat loss.
2. Winter Cold is Persistent
In Europe, North America, and Canada, cold is not just a few hours at altitude—it can last all day, for weeks or months. Urban travel, commuting, sightseeing, and long periods outdoors demand thermal wear that is comfortable enough to be worn for extended hours without overheating indoors.
What Makes a Good Thermal Suit?
A quality thermal suit balances warmth, breathability, and fit. The goal is not maximum thickness, but efficient insulation.
-
Insulation: Traps body heat without excessive bulk
-
Moisture Management: Moves sweat away from the skin
-
Stretch and Fit: Allows climbing, walking, and layering
-
Weight: Light enough to layer, heavy enough for conditions
Common Questions we get:
1. Do I really need thermals if I already have a heavy jacket?
Yes. Jackets protect you from wind and external cold, but thermals regulate your core temperature and manage sweat. Without a proper base layer, even the best jacket will feel cold.
2. Are thermal suits only for mountaineering?
No. The same thermals used on Mount Kenya are ideal for winter travel abroad—whether you are walking city streets, attending outdoor events, or commuting in cold climates.
3. Which is better: wool or synthetic?
-
Merino wool is excellent for cold, resists odour, and stays warm even when damp—ideal for multi-day climbs.
-
Synthetic materials dry faster and are often more affordable—great for travel and daily winter use.
4. How many thermal layers do I need?
Usually one good base layer is enough. In extreme cold (summit night or sub-zero winters), pair it with a mid-layer (fleece or insulated top) and an outer shell.
5. Should thermals fit tight or loose?
Thermals should fit snugly, not loosely. Close contact with the skin improves heat retention and moisture transfer.
6. Can I wear thermals all day?
Yes. High-quality thermals are designed for extended wear, whether you are hiking for hours or spending a full day outdoors in winter cities.
7. Do I need separate thermal tops and bottoms?
Ideally, yes. Heat loss occurs through the legs as well, especially in cold wind. A full thermal set offers balanced insulation.
Choosing Thermals for Your Specific Use Case
For Mount Kenya or Kilimanjaro
-
Prioritise warmth-to-weight ratio
-
Look for breathable, sweat-wicking fabrics
-
Avoid cotton—it retains moisture and makes you colder
For Winter Travel Abroad
-
Choose comfortable, soft fabrics for long wear
-
Neutral colours work well for layering under everyday clothes
-
Consider medium-weight thermals for versatility indoors and outdoors
Final Thoughts
Thermal suits are not optional accessories—they are essential systems that protect your body in cold environments. Whether you are pushing toward a summit in East Africa or navigating winter streets overseas, the right long johns allow you to focus on the experience, not the cold.
For Kenyan adventurers and travellers alike, investing in proper thermal wear is an investment in safety, comfort, and confidence—wherever the cold may find you.