It is good to hear that your case of cerebral palsy is relatively mild and that you have managed to have good function after surgery
It is certainly possible that you could have developed some arthritis
in the joints where you previously had surgery. Joint surgery can be a risk factor for arthritis later in life. You should talk to your primary care doctor
about this, as they will be able to examine the affected joints for any signs of swelling or other problems.
It is also true that people who have arthritis will sometimes state that they feel more stiff or sore with changes in the weather. Although this is a common complaint, there is not evidence that arthritis is objectively worse with changes in the weather, only that the perception of that arthritis is worse. This means that you do not have to worry about it particularly and could simply take a pain relief medication to relieve the symptoms.
Depending on your age (not clear from the question) there might be other reasons for you to be developing arthritis unrelated to your prior history of multiple surgeries. Again, I would begin by talking with your primary care doctor.