Complex sentence: This proved to be a misjudgments, as conditions were cooler in the Great Wall section--compared to--than on the previous day, and there were thunderstorms, resulting in persistently heavy rain and strong winds, which made preparations in tropical conditions useless.
Split into simpler sentences: This proved to be a misjudgments, as conditions were cooler in the Great Wall section--compared to--than on the previous day. Besides, the thunderstorms, resulting in persistently heavy rain and strong winds, made preparations in tropical conditions useless.