The rain can suddenly change or stop due to several meteorological phenomena such as the passing of a weather front or the end of a rainband or storm cell. Sudden heavy rain called a "cloudburst" may start as intense rainfall right from the onset, especially in warm conditions with high moisture content that causes strong updrafts and rapid condensation. Sometimes, rain suddenly changes into hail or is accompanied by strong winds, as in the case of a hailstorm that can cause instant damage to fields. Additionally, dust storms can carry particles that mix with rain, resulting in "dirty rain." Sudden changes in rain intensity are related to the dynamic and localized nature of weather systems, such as cold fronts, thunderstorms, or tropical storms passing through an area.
In summary, when rain suddenly changes or stops, it is often due to the rapid movement or dissipation of the cloud systems causing the rain or a change in atmospheric conditions such as temperature, moisture, or wind.
