I have small bumps on both of my index fingers. I don't know what it can be. Happens when it gets warm out.?

Doctor can evaluate. Rashes are quite hard to describe and diagnose in words. A primary dr. Or a dermatologist can look at it in order to tell what it is. If an eczema rash, Hydrocortisone cream helps. Itchy little bumps of 1-2mm size, that come and go on the fingers, may be dyshidrosis, a form of eczema. Some rashes are an allergy to something. A dr.'s exam can help, especially if few days of Hydrocortisone hasn't.