Irrigation scheduling software and apps integrate with weather forecast services through APIs or data feeds, which provide real-time weather data, including temperature, humidity, wind speed, and precipitation. This integration enables the software or app to adjust irrigation schedules based on current and forecasted weather conditions, ensuring that plants receive the right amount of water at the right time. For example, if a weather forecast predicts heavy rainfall, the software or app can automatically skip or reduce irrigation for that day, thereby preventing overwatering and minimizing waste.