From @OldGuyot "You may be able to regulate it by keeping the doors more open but that may not be practical in heavy rain."
This is an important thing that people overlook. When bad weather comes peoples inclination is to zip tent doors, and vestibules closed tight. When in fact it is far better to leave them open to promote air flow.
Anyone who has spent a hot night in a tent, knows that it is cooler in a tent with the mesh door zipped open. We need that same airflow on rainy days too!