In heat the deciding factor is not lower weight but moisture transport and ventilation. The working set: a combat shirt with a knit torso and cooling technology, a moisture-wicking T-shirt as the base layer, and shorts or light tactical trousers depending on the task.
Why it is hot under body armour even in moderate heat
A plate carrier covers chest and back with a solid panel: air does not move, sweat does not evaporate, the fabric soaks through and stops breathing. An hour into the work wet clothing starts to chafe, and in any draught it chills you — people catch colds in thirty-degree heat this way.
So the place to start is not the outer layer but what touches your skin. A lighter jacket solves nothing here.
What works in heat
| Layer | What to take | Why |
|---|---|---|
| Base | Moisture-wicking T-shirt or light base layer | Moves moisture to the outer surface where it can evaporate |
| Top | Combat shirt with knit torso | Cooling under armour, mesh underarm panel, ripstop sleeves for abrasion |
| Bottom | Shorts or light tactical trousers | Less weight where knee protection is not critical |
Why a cotton T-shirt is a bad idea
Cotton absorbs moisture and holds it against the body: the shirt becomes heavy, stops drying and chills you in the slightest wind. Most summer colds in the field trace back to exactly that. Wicking fabrics do the opposite — they carry moisture outward.
When shorts are the wrong call
Shorts are comfortable but leave knees and shins exposed to scratches, insects and sun. For static positions, rear-area tasks and training that is acceptable; for work in treelines and fortifications, light trousers are the better answer.
Common mistakes
- Choosing clothing by weight while ignoring moisture transport.
- Wearing a cotton T-shirt under a plate carrier.
- Skipping headwear and neck cover.
- Drinking too little on the assumption that light clothing will save you.
- Wearing shorts where knee protection is needed.
What light clothing does not do
No fabric lowers air temperature or replaces work-rest cycles, water and shade. Cooling technologies reduce discomfort, but they do not cancel the thermal load imposed by body armour.
Summer checklist
- A wicking base layer — not cotton.
- A combat shirt with a knit torso and ventilation.
- Bottom half chosen by task: shorts or light trousers.
- A spare set in a dry bag.
- Headwear and neck protection.
Frequently asked questions
What should I wear in heat?
A combat shirt with a knit torso, a moisture-wicking T-shirt as the base layer, and shorts or light tactical trousers depending on the task.
Why not cotton?
Cotton absorbs moisture and holds it against the body: the garment gets heavy, does not dry and chills you in a draught.
Does cooling fabric help under body armour?
It reduces discomfort and moves moisture, but it does not remove the thermal load. Work-rest cycles and water remain the main factors.
Shorts or light trousers?
Shorts for positions and rear-area tasks. For work in treelines and fortifications, light trousers protect against scratches, insects and sun.
Can a combat shirt be worn without body armour?
Yes. It also works as a standalone shirt: the sleeves handle abrasion and the knit torso breathes.
Author: Serhii Vynnyk, founder and CEO of UATAC. Updated: 16 September 2026.