is the noise coming from inside the car? if so, it could be the steering joint needs greasing, or abit of wd40. if it's on the outside the steering rack maybe on the way out.
when you next get in the car, turn the steering really slowly, and if it gudders, it's the power steering pump playing up. or it could even be cos it's damp out, the belt could be slipping. let me know mate.