Officials say at least 150 people, mostly women and children, have died in rain-related incidents in less than a month as monsoons lash Pakistan. AP / AFP

At least six people were killed in Karachi as another strong spell of monsoon showers lashed the metropolis overnight, submerging several parts of the city and inundating posh areas like DHA and Clifton on the second day of Eid Al Adha, officials said.

The Pakistan Meteorological Department (PMD) has forecast light to moderate showers in the metropolis on Monday under the influence of a strong weather system.

Most underpasses were flooded and there was nowhere to pump the floodwaters out to, the chief minister for Sindh province, Murad Ali Shah, told reporters. He said an unprecedented 126mm rain had fallen in three hours.

The streets of posh areas such as the Defence Housing Authority (DHA) complex and Clifton were flooded, with water gushing into houses.

"Deeply saddened by the tragic losses due to torrential rains in Karachi," Prime Minister Shahbaz Sharif said on Twitter. He offered every possible support for the Karachi administration.

Chief Meteorologist Sardar Sarfraz said the city is likely to receive intermittent light to moderate rain throughout the day due to a low-pressure's presence over the Arabian Sea. He said that cloudbursts cannot be predicted, adding that the current spell may weaken by July 13.

Sarfaraz said that another "strong" monsoon system is likely to enter Karachi from July 14. "Due to persistent low pressure over the North Arabian Sea, intermittent rain-thunderstorms of moderate/heavy intensity, very heavy at times, are likely to continue in Karachi, Thatta, Badin, Hyderabad, Mirpurkhas, Umerkot, T.M Khan, Tando Allayar and Tharparkar districts till 12 July evening," the PMD advisory said.

The Met Office added that scattered rain-thunderstorms are also expected in Sukkur, Larkana, Dadu, Jacobabad, Khairpur, Nawabshah, Noushero Feroz and Shikarpur districts during the period.

"The continuous rainy spell may create water logging/ urban flooding in low-lying areas of Karachi, Hyderabad, Thatta, Mirpurkhas, Umerkot and Badin."

Several main roads and streets were completely flooded as heavy rainfall once again exposed the city’s drainage system and the Sindh government’s claims regarding its rain emergency plans.

Karachi’s posh areas including DHA and Clifton were submerged due to heavy showers where rainwater entered homes with the masses slamming authorities for their negligence that has ruined their Eid.

According to the PMD data, Karachi received high amounts of rainfall in the last 24 hours.

Meanwhile, in a statement, Muttahida Qaumi Movement (MQM) lashed out at the Sindh government over its "failure” amid continuous heavy rainfall. "Rains have once again exposed the state of Karachi's infrastructure. The city’s sewerage system is choked with roads giving a view of ponds.”

The MQM, a key partner in the Shahbaz Sharif-led coalition government, said citizens are suffering due to the incompetence of the Sindh government. "The Sindh government ministers and officials are celebrating Eid in their home areas.”