I get yeast infection often in the summer why?

Heat, moisture : in vaginal area can make for optimum environment for yeast to grown. Especially if you wear tight panties or hose made from synthetic materials that don't "breath" well.

Yeast: Yeast normally lives in our body. When there are areas that are warm and moist it presents in other areas and multiples quickly. I hope this helps.

Yeast like moist: environments to grow. Sweating creates a moist environment. Wear cotton underwear and change frequently if you are sweaty. Also do not stay in a wet swimsuit all day.

See below: Heat and perspiration contribute. Please also be checked to be sure you don't have diabetes.