I have frequent numbness in my fingertips (most severe in pinky of right hand). is this the sign of something serious or is it just due to cold?

Numbness: This symptom may be due to a nerve impingement in the wrist by thickened ligaments( caused by prolonged computer usage). Another possibility is vasospasm upon cold exposure as seen in Raynaud's syndrome. If associated tingling occurs, deficiencies of calcium,magnesium and potassium are possibilities. See your physician or a hand surgeon for evaluation and advice.