The India Meteorological Department (IMD) recently released its first forecast for the 2025 monsoon on April 15, predicting above-normal rainfall. This forecast is closely monitored, not just by weather enthusiasts, but also by economists, since it significantly impacts crop yields and inflation. The June to September period typically accounts for about 75% of India’s annual rainfall, marking the official monsoon season.
Despite the excitement surrounding the IMD’s forecast, a recent analysis suggests caution. Historically, these forecasts have proven to be less reliable than flipping a coin. Interestingly, even when the overall rainfall prediction is accurate, it doesn’t always contribute positively to economic assessments.
The key figure in the monsoon forecast indicates expected rainfall in comparison to the Long Period Average (LPA), which is an average based on historical data from 1971 to 2020. For instance, this year, the IMD anticipates rainfall to be around 105% of the LPA, indicating an above-normal monsoon.
According to the Centre for Monitoring Indian Economy (CMIE), since 2001, the IMD’s first monsoon forecast has often missed the mark. Out of 24 forecasts leading up to 2024, 14 were off by more than five percentage points. With an error margin of up to five percent, the accuracy of these forecasts stands at only about 42%, which is notably worse than a simple coin toss, which has a 50% chance of being right.
In the cases where IMD’s forecasts were significantly off, actual rainfall was higher than predicted in six instances and lower in eight. This indicates a tendency for the IMD to be overly optimistic in its early forecasts. Nevertheless, it’s worth mentioning that the IMD has made improvements in recent years; only two of the inaccurate forecasts in the last five years deviated by more than five percentage points, compared to higher numbers in earlier periods.
Another important issue related to the monsoons is the growing variability in rainfall across different regions and times, even if the total predicted rainfall seems adequate. For example, last year, the IMD projected 922 mm of rain, but the actual total was 936 mm. However, the actual rainfall varied significantly across the country, with some areas receiving much more or much less than others, indicating an uneven distribution. This inconsistency is believed to stem from climate change, complicating the forecasting process.
While the IMD does attempt to account for regional differences in its forecasts and provides the likelihood of rain for various areas, the information isn’t always presented in a way that allows for effective assessment of its accuracy. As the monsoon season approaches, stakeholders will be watching carefully to see how these forecasts hold up.
