Silk has the unique ability to absorb up to 10-30% of its weight in moisture, which makes it a fairly breathable fabric. Plus, it's lightweight and thin, making it perfect for warmer temperatures.
Loose silk clothes and silk scarves are especially useful in the summertime.
However, it's important to note that silk isn't as absorbent as cotton, which is made from vegetable fibers. While silk can deal with some sweat, it's best to avoid tight silk clothing that's close to your skin, such as silk underwear.
In tropical climates, opt for loose silk clothing like tank tops or maxi dresses to help keep you from getting too sweaty.