Weathernews Adds AI-Nowcast to App for 3-Hour Rain Forecasts
Weathernews says AI-Nowcast, trained on six years of data, powers My Weather icons and precipitation forecasts in its app.
Weathernews announced that it has fully implemented AI-Nowcast, its proprietary AI weather forecasting model for rain predictions up to three hours ahead, in the Weathernews weather app. The company said AI-Nowcast is used for the weather icons and precipitation forecasts shown in the app's My Weather feature.
According to japan.cnet.com, the model was trained on six years of data to learn patterns of rain cloud generation, development, movement and decay. The training set combined weather radar, observation data from various locations and the company's own analysis data based on user weather reports (Weather Reports), and the model also reflects real-time observation data in its predictions.
Accuracy verification
In a comparison using data from August 9 to September 8, 2026, the capture rate for predicting strong rain of 10 mm or more per hour without missing it improved by 8 points at one hour ahead and by 10.1 points each at two and three hours ahead versus the conventional model.
The threat score, a forecast accuracy index that accounts for both missed rain and false alarms, improved to about 1.3 times the conventional level at one hour ahead and about 1.6 times each at two and three hours ahead.
Weathernews notes that these are its own verification results and that the same accuracy improvement may not be obtained under all weather conditions.
Quick answers
What is AI-Nowcast?
It is Weathernews' proprietary AI weather forecasting model for rain predictions up to three hours ahead, now used in the Weathernews app.
Where is AI-Nowcast used in the app?
It is used for the weather icons and precipitation forecasts shown in the app's My Weather feature.
How accurate is AI-Nowcast?
Weathernews reports its own verification results: the capture rate for strong rain of 10 mm or more per hour improved by 8 points at one hour ahead and 10.1 points each at two and three hours ahead, and the threat score improved to about 1.3 times and about 1.6 times the conventional level, respectively. The company notes the same improvement may not be obtained under all weather conditions.