Temperatures in excess of 40 degrees Celsius are expected to prevail in Karachi until May 4 as a heatwave enveloped the city on Tuesday morning, the Met Office said, a day earlier than was previously anticipated.

A heatwave alert posted on the Pakistan Meteorological Department's (PMD) website stated that the metropolis started experiencing a heatwave since the morning with hot winds blowing at 10-15 knots from the northwest. It added that the maximum temperature in Karachi today may go up to 42 degrees Celsius.

According to the Met Office, the extreme weather conditions could continue for the next four days until May 4.

The department called on all stakeholders to take precautionary measures and remain updated on the situation.

Earlier on Saturday, the Met Office had announced that a heatwave was likely to grip Karachi between May 1 and May 3. However, the city started to experience extreme weather conditions a day early.

Read: Five things to do for heatwave management in Karachi

With the city bracing for the heatwave, heatstroke wards have been set up at government hospitals and an emergency has been declared for the treatment of those affected by the extreme heat. Heatstroke camps have also been set up across the country's largest city.

Dr Nauman Nasir at the Abbasi Shaheed Hospital (ASH) said that along with all other Karachi Metropolitan Corporation (KMC) hospitals, an emergency had been declared at the ASH in order to treat those affected by the heatwave.

Speaking to DawnNewsTV, Dr Nasir said that all arrangements for the heatwave had been completed at the hospital, where a 45-bed heatwave ward has been set up.

He advised Karachiites to eat light foods and drink more water during the period of hot weather.

Read: How to prevent and cure heatstroke

Meanwhile, Sindh Inspector General (IG) of Police Dr Syed Kaleem Imam directed authorities to set up heatstroke camps where cold water and drinks are provided.

He said steps should also be taken to create awareness about heatstrokes among the people. In order to prevent citizens from experiencing heatstrokes, the process of providing initial medical aid should be made possible, he added.

IG Imam called on senior superintendents of police (SSPs) traffic to set up heatstroke camps at the zonal level.

With additional reporting by Imtiaz Ali in Karachi.