In this paper, we present an analytical noise modeling methodology for lateral nonuniform MOSFET. We demonstrate that the noise properties of lateral nonuniform MOSFETs are considerably different from the prediction obtained with the conventional Klaassen-Prins (KP)-based methods which, at low gate voltages, depending on the doping profile can overestimate the thermal noise by 2-3 orders of magnitude. We show that the presence of lateral nonuniformity makes the vector impedance field (the quantity responsible for noise propagation) position and bias dependent. This insight clearly explains the observed discrepancy and shows that the bias dependence of the important noise parameters cannot be predicted by conventional KP-based methods.