India's commercial capital Mumbai was lashed by rain on Wednesday while a dust haze shrouding northern parts of the country cooled temperatures after a heat wave that has killed more than 1,400 people.
The heat has also killed about 100 people in neighbouring Pakistan and Bangladesh.
Children splashed in puddles in Mumbai, on India's western coast, as they celebrated the city's first rains this summer, which came as a huge relief after weeks of sweltering heat.
The pre-monsoon showers precede what should be torrential downpours within a few weeks.
The arrival of the June-September monsoon is of great importance on the sub-continent. About 70 percent of India's one billion people live off farming and the monsoon is the sole source of water for crops in many parts of the country.
The monsoon hit the southern state of Kerala on Sunday, a week late, and is slowly spreading across the rest of the country. It is likely to reach the northern plains by the end of the month.
But temperatures dipped slightly in the north on Wednesday because of the haze, brought in by strong desert winds from Rajasthan.
"The dust haze will continue for the next two days and it will bring temperatures down further," an Meteorological Department official told Reuters.
But temperatures dipped slightly in the north on Wednesday because of the haze, brought in by strong desert winds from Rajasthan.
"The dust haze will continue for the next two days and it will bring temperatures down further," an Meteorological Department official told Reuters.
Flash floods caused by heavy rains also hit neighbouring Bangladesh, where 40 people have died in the heat wave.
Hyderabad, the capital of India's worst-hit state of Andhra Pradesh, was at a cooler 39 degrees Celsius (102.20 F) after pre-monsoon showers in the city.
The bulk of the 1,400 deaths in India have been in Andhra Pradesh - most of them street hawkers, beggers and the homeless - who fell victim to sunstroke and dehydration.