The rainfall, which began early in the day, has ended a prolonged spell of intense heat, providing a much-needed respite for residents.
The Pakistan Meteorological Department (PMD) has forecast intermittent rain and thunderstorms throughout the day, especially after noon.
Temperatures are expected to peak at 31°C, with high humidity levels remaining around 90%. Winds are blowing from the northeast at 10 km/h, contributing to the cool yet damp conditions.
The PMD has also predicted thundershowers for other cities in Sindh, including Hyderabad, Dadu, Badin, and Sukkur.
The ongoing westerly system is expected to bring thunderstorms, gusty winds, and more rain to the region until June 29.
In Karachi, the highest rainfall recorded so far has been 16mm in Surjani Town, followed by 7.4mm in North Karachi and 6.1mm in Orangi Town.
The Met Office has issued a warning that another monsoon system will likely affect Sindh around July 5 or 6.
The PMD spokesperson noted that the southern parts of Karachi are currently under cloud cover, which could lead to heavier rainfall later in the day.
Residents are advised to remain cautious on the roads, as wet conditions could lead to slippery surfaces.