The pre-monsoon rainfall in the country was the second lowest in 65 years, private weather forecaster Skymet Weather said. The three-month pre-monsoon season March, April and May ended with a rainfall deficiency of 25 percent.

All the four meteorological divisions - Northwest India, Central India, East-Northeast India and South Peninsula - recorded deficit rainfall of 30 percent, 18 percent, 14 percent and 47 percent, respectively, Skymet said.

Pre-monsoon rainfall colloquially referred to as "mango showers", is vital to many parts of the country. In states like Odisha, ploughing is done in the pre-monsoon season and in parts of northeast India and the Western Ghats, it is critical for plantation of crops.

Further, the India Meteorological Department said the onset of monsoon is likely to be delayed by a week and it is now expected to arrive only by June 8.

The normal onset date for monsoon over Kerala is June 1 which also marks the official commencement of the four-month-long rainfall season. Private weather forecaster Skymet too revised its forecast from June 4 to June 7.

Last month, announcing the expected day of monsoon arrival over Kerala, the IMD had said it could happen on June 6, with an error margin of plus or minus four days. The Met Department has given a forecast of a normal monsoon for the season.

Several parts of the country are reeling under severe heatwave with temperatures touching 50 degrees Celsius in some parts. The arrival of monsoon is likely to give some respite from the scorching heat.