India's monsoon is advancing after stalling for more than a week and rains are set to cover central parts of the country in the next few days, bringing relief from the heatwave in the grain-growing northern plains, two senior weather officials said.

Summer rains, critical for economic growth in Asia's third-largest economy, usually begin in the south around June 1 before spreading nationwide by July 8, allowing farmers to plant crops such as rice, cotton, soybeans, and sugarcane.

"Monsoon is reviving. It was stuck after covering most of Maharashtra, but by the weekend, it will enter Madhya Pradesh," an official of the India Meteorological Department (IMD) told Reuters.

"Western and southern regions will receive heavy rains from the next week. Central parts would also start getting rains," added the official, who spoke on condition of anonymity because they were not authorised to speak to the media.

The monsoon arrived nearly two days ahead of schedule in the western state of Maharashtra, home to the commercial capital of Mumbai, but its progress in central and eastern states of the country stalled for nearly a week.

The lifeblood of the nearly $3.5-trillion economy, the monsoon brings nearly 70% of the rain India needs to water farms and refill reservoirs and aquifers.

In the absence of irrigation, nearly half the farmland in the world's second-biggest producer of rice, wheat and sugar depends on the annual rains that usually run from June to September.

The monsoon is expected to advance swiftly from next week and bring down temperatures in northern India, another weather official said.

The heatwave in northern states will ease by the weekend, he said.

The maximum temperature in India's northern states ranges between 42 degrees Celsius and 46 degrees C (108 degrees Fahrenheit to 115 degrees F) this week, which is nearly 3 degrees C to 5 degrees C above normal, the IMD data showed.

India has received 18% less rainfall than normal since the season began on June 1, the IMD says.