Is rheumatoid arthritis worse in summer?

Not usually: Most people with rheumatoid arthritis report that their symptoms get worse in the winter and more people are diagnosed in the winter months. Of course, it's possible that your disease gets worse in the summer.

Not usually: Many things can contribute to an exacerbation of your arthritis. Heat usually helps with joint complaints, but weather changes can worsen symptoms.

Not well studied: To my knowledge, I've not read that rheumatoid arthritis (RA) symptoms are better or worse in any season. There have been some recent studies suggesting that the change in barometric pressure may effect some types of arthritic symptoms. However this is not specific to RA.

See below: It is the changes in barometric pressure as any fluid in your joints can expand or shrink with changes in barometric pressure.

Not per se, but:: If you have frequent bouts of rain or severe weather, a fall in barometric pressure preceding a storm will increase joint pain.