don't paint at 6 degrees or less. If its damp don't paint. Alway try to paint under cover, and be wary of diesel space heaters as they throw out particles which will contaminate your paint.
sprayed some items last night, prepped them first, hung on the radiator to warm through, then out into the workshop, a light 'mist' coat. wait 'till touch dry, then a nice even full coat. Once touch dry, back indoors hung to go off overnight.Even touch dry if you leave them out it can bloom (milky dull finish) and probably be running in condensation!