dark but not to wet just a light drizzle and plenty of wind ,keep the wind in your face then the rabbit wont scent or hear you coming ,just keep flicking the lamp on to pick them out ,in other words dont walk round like some do with the lamp on full bore all the time looking for the rabbits ..
forgot to say rabbits move out more in to the field later on in the night as they feel more at ease after they have been feeding for a while ..