my legs and knee area always seems to pain when the weather is damp. does this happen to anyone else? could it be arthritis??? are there any tests that the doctor can do to determine whether its arthritis or not? thanks for your help!

It most certainly can be arthritis, particularly Osteoarthritis. Are you an active indiviudal or possibly did sports or the like in the past? OA is caused by deterioration over time by stress or injury on the joints.
The doctors can in fact do x-rays as well as blood work to see if you have arthritis. The key to bloodwork however when it comes to OA is to have it tested during a flare up, not when you are feeling well. The reason is the SED red, which is used to determine imflamation will be low on a good day, high on a bad day.

If you do have OA or any other form of arthritis they can put you on anti-imflamatories. In the mean time you can use acetaminophen products like Tylenol or ibuprofen to help with the swelling and or pains.
Do not take more than 4000 mg of tylenol type products in a 24 hour period however as this can damage the liver.