Based on the weather,there are two different weather conditions trekkers faced on trekking days on volcanoes: cold and hot sunny day.In good weather,tiredness could be problem: body temperature can drop where warming is necessary.
The windbreaker jacket is a safety feature on a trekking day,even in good weather, as it can keep warm in case of injury or tiredness.Today windbreaker jacket come to vary in mode,the good one is normally the heavier mode,but effective against cold, even rain.
Another important trekking item in cold weather is glove, it's beneficial increased at night camp on high altitude and early morning cold conditions or on time of tackling cold windy track. Different to other trekking items,glove has almost come in similar mode but normally different in thickness, thicker one is generally more appreciated to bring on multiple day trekking on high to very high volcano / mountain.
There many options trekking clothes in fact, some trekkers like to wear long t-shirt while other are not. T-Shirt with long sleeves can be a good solution in afternoon hot weather,because it protects against sunburn.When it is hot,a T-shirt mode with a zip front opening makes it easy to regulate body temperature. On sunny days,a T-shirt with light color is better suited than a dark one since it concentrates the heat.In contact with the skin, the first layer of T-shirt must be breathable and dry quickly for your trekking