To extract the temperature gradient profile inside heating droplets using the Rainbow Refractometry technique, light scattering of a multilayered sphere illuminated by a Gaussian beam is applied to simulate the rainbow pattern of a radially inhomogeneous heating droplet in the case of a laser beam illumination. The analysis is implemented within the framework of Generalized Lorenz–Mie Theory (GLMT) by using a stable numerical algorithm developed recently based on theoretical reformulations and calculations of various auxiliary functions. Influences of the layer number of the multilayered sphere, beam waist radius of the Gaussian beam, and location of the droplet in the Gaussian beam on the rainbow pattern are analyzed. The least number of layers used to model a continuous profile of refractive index can be determined based on the analysis of Airy pattern. Both the Airy pattern and the angular position of its first maximum are high sensitive to the refractive index profile of the droplet. The results show that the influence of the beam waist radius should be taken into consideration if the beam waist radius of the beam is less than the radius of the droplet. While the angular position of the first peak in the Airy pattern changes little if the beam waist radius of the Gaussian beam is much larger than the diameter of the droplet.