How We Achieved 85% Rainfall Forecast Accuracy (Technical Deep Dive)

Advanced technology ensures highly accurate weather forecasts.

Weather forecasting is essential for planning human activities, especially in regions prone to extreme events, such as the state of Rio de Janeiro. However, many forecasts are still generic and fail to capture local variability. Cittua has developed its own model, with extremely high spatial resolution, capable of delivering forecasts with over 85% accuracy. In this post, we explain how this technology works and why it represents a significant advancement in applied meteorology.

1. Weather Forecast: Why Local Accuracy Matters

Weather forecasts affect sectors such as agriculture, transportation, energy and risk management. In cities like Rio de Janeiro, where the topography is complex, generic forecasts often fail to capture the actual rainfall distribution. Local accuracy allows for more effective warnings and decision-making based on real data.

2. Applied meteorology: from theory to practice

Meteorology has evolved with the use of numerical models that simulate atmospheric behavior. Cittua combines this knowledge with cutting-edge technology, creating models that respect atmospheric dynamics with high spatial granularity.

3. Climate technology: the basis of Cittua's innovation

Our model operates with nested grids at 3km and 1km resolutions, offering highly localized forecasts. It updates every 12 hours, predicting events for the next 48 hours with unprecedented detail.

4. Weather forecast focusing on observed reality

We used data from sensors, satellites and a unique hyperlocal numerical model as our basis. The Cittua model’s predictions were compared with observed data between April 4th and 7th, 2025, demonstrating accuracy of over 85%.

5. Accurate Weather: Localized and Reliable Forecasts

With 1km resolution, it’s possible to more accurately predict where and when rainfall will occur, even in small areas with uneven topography. This was demonstrated in case studies of the Serrana Region and the Metropolitan Region of Rio de Janeiro.

6. Advanced climate models and their performance metrics

We used metrics such as accuracy and relaxed accuracy to measure model performance. The results showed a high level of agreement between forecast and observation in both rainfall occurrence and intensity.

7. High-quality weather data as a differentiator

Forecast quality depends on data quality. Cittua uses dense rainfall measurement networks, historical data and atmospheric information from a variety of reliable sources to feed its models.

8. Artificial intelligence as an ally in forecasting

AI allows us to analyze large volumes of weather data and identify complex patterns in seconds. This capability accelerates model adjustments and improves real-time accuracy.

9. Climate analysis by period and location

Cittua’s forecasts consider specific periods of the day (morning, afternoon, evening and dawn), offering greater detail and accuracy. This is essential for critical applications such as civil defense and outdoor events.

10. Machine learning and continuous learning

The model learns from its own successes and failures, automatically adjusting itself. This reduces future deviations and increases reliability in different meteorological contexts.

11. Climate sensors and real-time collection

Real-time data collection is performed by automated temperature, humidity, wind and precipitation sensors. These sensors continuously feed the model, ensuring consistently up-to-date forecasts.

12. Meteorological big data for smart decisions

We process large volumes of information by cross-referencing meteorological data with topography, land use and historical events. This enables risk anticipation and effective planning.

13. Continuous and preventive climate monitoring

Our system monitors weather conditions in real time and automatically adjusts forecasts. This enables rapid responses in critical situations.

14. Weather satellites and macro view of the atmosphere

We use satellite imagery to complement local data, allowing us to identify large-scale systems such as cold fronts and storm formations.

15. Climate innovation as an ongoing commitment

Investimos em pesquisa e desenvolvimento constante, parcerias com instituições científicas e expansão de nossa infraestrutura tecnológica. Nosso compromisso é com a precisão e a segurança de nossos usuários.

The technology developed by Cittua demonstrates that it’s possible to predict the weather with high accuracy even in complex regions. Combining advanced spatial resolution, AI, sensors and rigorous validation, we deliver weather forecasts with over 85% accuracy. This means greater safety, more planning and fewer weather surprises for everyone.