Agence France-Presse, citing Provincial Health Secretary Saeed Mangnejo, reported 122 people have died since Saturday.
Saturday's temperature reached 44.8 degrees Celsius (112.64 degrees Fahrenheit), which is the highest-recorded temperature in Pakistan in the past 15 years, according to CNNI senior weather producer Taylor Ward.
Sunday's temperature dipped to 42.5 Celsius (108.5 F), and that slight temperature decline will continue over the next few days, he said.
Most Pakistanis are observing Ramadan, meaning people are fasting from sunup to sundown during the heat wave, CNN News Editor Archith Seshadri said.
Agence France-Presse reported that 47.0 (116.6 F) is the highest temperature reported in June in Karachi. The Pakistani government says 47.8 (118.04 F), recorded in May 1938, is the all-time high.
