Measuring temperatures at small scales, especially around nanoparticles, is a crucial step for a variety of applications in biomedicine and in optics. Here, we report on a novel method to map temperature in the medium surrounding silver nanoparticles dispersing them in a thermochromic mixture prepared using an organic dye and a polymer. When the nanocomposite is irradiated with visible light, nanoparticles convert light into heat and the nanocomposite changes its colour. The temperature around silver nanoparticles can be, then, easily evaluated from this colour variation. The proposed method can be implemented in temperature monitoring devices of the nanoparticles surrounding media.