Based on the statistics during 1891-2017, on an average 5 cyclones develop over North Indian Ocean in a year with 4 developing over Bay of Bengal and 1 over Arabian Sea. However, in the recent past increase in frequency had been observed in formation of cyclones in the North Indian Ocean. Also studies show an increase in frequency of severe cyclones over Arabian Sea in recent years.
The details of Cyclones formed over North Indian Ocean during 2017 to 2019 follow:
| YEAR | Frequency of Cyclones over | Total number of cyclones | Intensity with that of Severe Cyclones or more | |
| Arabian Sea | Bay of Bengal | |||
| 2017 | 1 | 2 | 3 | 2 |
| 2018 | 3 | 4 | 7 | 6 |
| 2019 | 5 | 3 | 8 | 6 |
The occurrence of 5 cyclones over Arabian Sea in 2019 against the normal of 1 per year equals the previous record of 1902 for the highest annual cyclone frequency over Arabian Sea. Also 2019 witnessed development of more intense cyclones over Arabian Sea.
Regarding flood, it is mentioned that, the country has witnessed intense to very intense rainfall activity leading to flood scenario in the recent past. The number of stations reported Very Heavy and Extreme Heavy rainfall in the last three years, from 2017 to 2019, follow:
| YEAR | Number of stations reported during SW Monsoon season (June to September) | |
| Very Heavy Rainfall (115.6-204.4 mm) | Extremely Heavy Rainfall (204.5 mm or more) | |
| 2017 | 1824 | 261 |
| 2018 | 2181 | 321 |
| 2019 | 3056 | 554 |
The data shows that there is a steady increase in the number of heavy rainfall events during the last three years.
IMD uses a suite of quality observations from satellites, radars and conventional & automatic weather stations for monitoring of cyclones and prediction of weather. It includes INSAT 3D, 3DR and SCATSAT satellites, Doppler Weather Radars (DWRs) along the coast and Automated Weather Stations (AWS), Automatic Rain Gauges (ARGs), meteorological buoys and ships. Operational implementation of improved suite of prediction models has enhanced the weather forecasting capability through assimilation of all available global satellite radiance & Radar data for the production of forecast products at 12 km grid globally and 3 km grid over India/regional/mega city domains.
Further improvements in the observational network and numerical modelling are in progress under the scheme Atmosphere & Climate Research – Modelling Observing Systems & Services (ACROSS) for betterment of forecasting natural disasters like cyclone and heavy rainfall with respect to accuracy, lead time and spatial resolution.
This information was given in a written reply by the Minister of Science and Technology, Earth Sciences, and Health & Family Welfare, Dr Harsh Vardhan in Lok Sabha on September 23, 2020.