Caution Advised: IMD’s Monsoon Forecasts and Their Implications
The IMD’s initial 2025 monsoon forecast predicts above-normal rainfall, but historical analysis shows only 42% accuracy, akin to a coin toss. Variability in rainfall distribution complicates economic assessments, necessitating caution despite optimistic projections.
The India Meteorological Department (IMD) issued its first monsoon forecast on April 15, projecting above-normal rainfall for 2025. This forecast is significant due to its implications for agriculture and inflation, as 75% of India’s annual rainfall occurs during the June-September monsoon season. Despite the optimistic forecast, a detailed analysis indicates a need for caution regarding its reliability.
The forecast estimates rainfall relative to the Long Period Average (LPA), which represents the historical average from 1971-2020. A deviation from the LPA within 4% is considered normal monsoon rainfall. This year, the IMD predicts rainfall at 105% of LPA, indicating an above-normal season.
A review by the Centre for Monitoring Indian Economy (CMIE) of IMD’s forecasts since 2001 reveals that in 14 out of 24 years, the forecast deviated from the actual rainfall by more than five percentage points. IMD’s forecast possesses an error margin of up to five percent, yielding only a 42% accuracy rate, inferior to the 50% probability of a coin toss.
Analysis shows six instances where actual rainfall exceeded forecasts and eight where it fell short, suggesting IMD forecasts tend to be overly optimistic. Nevertheless, their accuracy has improved slightly in recent years, with only two inaccurate forecasts from 2019 to 2024, compared to higher error rates in previous five-year periods.
A critical point of analysis is the geographical and temporal variability of rainfall, despite headline figures suggesting a specific amount. In 2024, the IMD forecast total monsoon rainfall at 922 mm, while actual rainfall reached 936 mm. However, rainfall distribution was uneven, with 41% of India experiencing over 120% of LPA, and 19% receiving less than 80%. This uneven distribution complicates predictions and suggests significant climate-related variations in rainfall patterns.
The IMD has acknowledged these variations by including regional forecasts in their predictions, indicating whether rainfall will likely fall within normal ranges for specific locations. However, the format of this regional data makes it difficult to evaluate its accuracy effectively.
In conclusion, while the IMD’s first forecast projects above-normal monsoon rainfall, historical data suggests caution due to inaccuracies and increasing variability in rainfall patterns. The lack of reliability in predictions, compounded by the effects of climate change, makes it challenging to draw definitive economic conclusions from these forecasts. Continued assessment and improved methodologies are essential for better forecasting accuracy in the future.
Original Source: www.hindustantimes.com
