Hi fighter! I know that many of our members find humidity to be a common trigger for MS symptoms. Really, any weather can potentially affect MS, including cold, rain, barometric pressure shifts, etc. Some of our member find that heat really does them in, while others cannot tolerate the cold. And others still just cannot handle shifts in temperature, such as going from the outdoors into an air-conditioned building. I want to mention that some folks do struggle with humidity, regardless of whether it's hot or cold outside, so if that's what you're experiencing, you are not alone! I hope this answers your question and thanks so much for reaching out! Best, Erin, MultipleSclerosis.net Team Member.