No, melting snow is not a chemical reaction; it is a physical change.
When snow, which is made up of ice crystals, melts, it transforms from a solid state to a liquid state, specifically water. This process occurs when temperatures rise above 0 degrees Celsius (32 degrees Fahrenheit), causing the ice molecules to gain energy and move apart, resulting in melting.
In a chemical reaction, the composition of the substance changes, forming new substances with different properties. For example, if you were to burn wood, it would chemically react with oxygen to produce ash, carbon dioxide, and other substances. In contrast, when snow melts, the water remains H2O, and no new substances are formed; thus, it is merely a transition between physical states: solid to liquid.