A little insight to why we include a mesh lining in select windbreaker styles. What's good for you is good for us.
The synthetic fiber content acts as a wick to pull the moisture away from your skin, while the mesh composition acts as a suspension system that increases airflow by maintaining separation between your skin/undershirt and the remainder of the garment. The wicking and increased airflow increases the rate of evapotranspiration, which allows your body to maintain a more consistent comfort level without the need to add or remove layers.
In other words, you keep the warmth without getting too sweaty.