How do you say "Thursday will be cloudy" in Chinese
"thursday will be cloudy" means "星期四（是）阴天" or "星期四（是）多云". 

有风 means 'windy', not 'cloudy'. 

We usually say "星期四（天气）（会）很热”, "星期四有风”, "星期四(是)晴天”， "星期四有雨”， "星期四（可能）（会）下雨” and etc.