Why we test in the rain

A garment that feels perfect on a dry day can behave very differently once it is wet. That is why wet-weather testing is a fixed part of how we develop every range, and why some of our best discoveries have come on the worst days.

This article explains what we learn from the rain, how we test, and how the results shape the clothes that reach you.

What rain reveals

Wet fabric gets heavier, clings differently and changes how seams sit against the skin. It shows us where water collects, where fabric chills and where a small rub becomes a real problem over distance. A garment that stays light and smooth when wet is a very different thing from one that sags, sticks and chafes.

Rain also changes how heat moves. Wet clothing conducts heat away from the body faster, which is welcome in a hot race and dangerous in the cold. We test how quickly garments dry, how warm they stay when damp and how they feel against the skin at different temperatures.

The difference between water resistant and waterproof

Water-resistant fabrics shed light rain but let water through if it falls hard or for long enough. Waterproof fabrics block water entirely but can trap sweat, leaving the wearer wet from the inside. The right choice depends on the activity. Running in a shower calls for a light, breathable layer that dries quickly; walking in a downpour calls for a true shell.

We test both properties together, because a jacket that keeps the rain out but holds the sweat in is not much use. Breathability is measured in the lab and checked in the field.

From the field to the pattern table

Athletes and club teams run, ride and train in prototypes in poor conditions, then tell us what they felt. Their comments go straight to our designers, who adjust patterns, seams and fabric choices before the next round. A comment such as “the sleeves soak up water and drag” leads to a change in cuff construction. A comment such as “my shorts rub when wet” leads to a different seam position.

The most useful tests are often the least pleasant. A cold, wet descent when everything is going wrong teaches us more than a sunny afternoon. We ask testers to be honest, especially about what is uncomfortable, and we try to respond quickly.

Rain and visibility

Wet weather often comes with poor light, so we test visibility at the same time. Reflective elements behave differently on wet fabric, and bright colours can look dull under grey skies. We check that reflective details stay effective in rain and that garments remain visible in low light.

Durability in wet conditions

Rain tests are also durability tests. Wet fabric is more prone to abrasion, and water can reveal weaknesses in seams, prints and finishes. We check that water-repellent treatments last through washing, that seams stay sealed and that prints do not peel or crack when soaked.

What we have changed

Wet testing has led to concrete changes. We moved seams on shorts after testers reported chafing in the rain. We changed the cuff on a running jacket so water did not run down the sleeve. We adjusted the fabric weight in a base layer so it stayed light when damp. These are not glamorous improvements, but they are the ones people notice on a bad day.

Testing for a changing climate

Weather is becoming less predictable. Heavy rain, sudden storms and temperature swings are more common in many places. We want our clothing to cope with all of them, so we design for a wider range of conditions than we once did, and we keep testing as the weather changes.

What you can do

If you train in wet weather, wear layers you can adjust, choose fabrics that dry quickly and avoid heavy cotton, which stays wet and cold. Carry a dry top for after your session, and wash and dry wet kit promptly. If you have feedback on how your kit performs in the rain, use the contact page and tell us. We are always looking for more testers, and for more bad weather.

The goal is simple: a garment that works as well in a downpour as it does in the sun.

Layering for wet days

A good wet-weather system has three parts. A snug base layer moves moisture away from the skin. A mid-layer, if needed, holds warmth. An outer layer sheds rain and wind while letting moisture escape. Keep each layer light so you can add or remove it as the weather changes, and choose cuffs, hems and hoods that adjust easily with cold or wet hands. The best layer is the one you will actually wear, so comfort and fit matter as much as the technical specification.

Questions about wet-weather kit

Should I wear cotton in the rain?

Avoid it. Cotton soaks up water, becomes heavy and stays wet and cold. Synthetic and wool blends dry faster and keep their warmth when damp.

How can I keep my feet and hands comfortable?

Wear quick-drying socks and gloves, and carry a dry pair in a bag if you can. Cold, wet extremities lose comfort first, and can make an otherwise good session miserable.

Is it safe to train in the rain?

In general, yes, but take care. Wet surfaces are slippery, visibility drops and conditions can change. Choose routes and surfaces carefully, wear bright clothing and adjust your pace. Avoid training outdoors during thunderstorms.

Join our test panel

We are always looking for more testers, and we are happy to hear from people who train in all kinds of weather. If you would like to be considered, tell us a little about yourself, where you train and what you wear, using the contact page.

About JISDO

JISDO Sportswear designs performance apparel for athletes and everyday movers. Media enquiries: hello@jisdo.com.