Being raised in a zone 9 I never even realized I had raynaud's until I took my first trip to the mountains in my 20's. My fingers and toes first turn red then pure white. The pain I can describe as having nails driven through your fingernails. I learned that snow skiing is not for me! Even good gloves won't keep me pain below 40! Even when active. Now at age 69 and living in a region with colder winters it is no worse but am always prepared. Like many I carry a pair of gloves and always bring a jacket (others mentioned keeping the core warm) to movie theaters and restaurants even in the summer if air conditioning is too cold. I have a pair of flexible soft leather gloves with rabbit hair lining which feel heavenly and I put on when shopping in produce isles. Water does trigger the loss of hand temp and wet produce can quickly turn my fingers white in a cool grocery. Then what can I do, basically nothing except hope the bathroom has warm water to run over my fingers. A surprisingly helpful way to warm up white toes, besides layers of blankets(which are surprisingly unhelpful once feet are white) or a heating pad is to wear a warm hat! Your body wants to keep the circulation in your brain #1 and if it has good blood flow it will send blood out to other areas. Also because I love to garden and stay out past my outdoor temp trigger points the fastest way to recover I have found is to put a washcloths in a microwave, heat till very warm, not scalding and wrap around fingers. This will get the blood flowing, first fingers will return from white to bright red and hurt like heck, then in a few minutes can return to flesh color and stop hurting.
I have read that those of us born with it have a genetic predisposition to having it and although painful and inconvenient it is not normally a significant health issue. For those who develop this later in life it is a signal that something else may be going on in your body like RA.