New Delhi: The southwest monsoon, which regained momentum this week, is expected to cover most parts of northwest India, including Delhi, by June 25, well ahead of the usual dates.

The primary rain-bearing system reached Kerala on May 24, marking its earliest onset over the Indian mainland since 2009, when it arrived on May 23. Aided by strong low-pressure systems over the Arabian Sea and the Bay of Bengal, the monsoon advanced quickly over the next few days, covering parts up to central Maharashtra, including Mumbai, and the entire northeast by May 29.