Weather forecasts are nothing more than calculations of probabilities. Rain probabilities are often used to indicate the risk of precipitation for an entire day.
Even with high values, it doesn't necessarily mean that the whole day will be rainy. The larger the rain areas and the shorter the forecast horizon, the more reliable the forecast. In the future, artificial intelligence may further improve weather forecasts. At the end of 2023, Google's subsidiary Google DeepMind presented current plans for an AI application. Other companies such as the Chinese company Huawei and the European Center for Medium-Range Weather Forecasts (ECMWF) have also entered the race.