Many other higher temperatures have been reported in the past but none are credible, he said.
Iraq's state-run Meteorological Department said on Saturday that it had registered the hottest day so far this year, with maximum temperatures hitting 53.9 degrees Celsius (129.02 Fahrenheit) in the southern city of Basra.
Friday's merciless heat in Basra forced the majority of the residents to almost abandon the streets or to swim in the river. Increasing the residents' suffering were chronic electricity outages, caused mainly by the soaring temperatures and the decline in electricity imported from neighboring Iran.
Starting from Saturday, temperatures are expected to hover around 49 degrees Celsius (120.2 Fahrenheit) in Basra and continue to decline in the coming days, weather forecaster Nagham Mohammed told The Associated Press.
Mohammed added that temperatures in Baghdad are expected to reach 45 degrees Celsius (113 Fahrenheit).
Weather historian, Christopher C. Burt, with the private Weather Underground, said Basra's temperature is the second hottest "ever reliably measured on Earth" following the 54 degrees Celsius (129.2 Fahrenheit) registered in Kuwait the same day.
The Kuwait's reading ties Death Valley's 54 degrees Celsius (129.2 Fahrenheit) one, which was measured on June 30, 2013 as the hottest reliably measured air temperatures on Earth, Burt added. Many other higher temperatures have been reported in the past but none are credible, he said.
On Wednesday, temperatures soared up to 51 degrees Celsius (123.8 Fahrenheit) in Baghdad and as much as 53 degrees Celsius (127.4 Fahrenheit) in Basra. The day before, the government announced a two-day mandatory official holiday beginning Wednesday in the first such heat-related holiday declared this summer. It is not uncommon for such public holidays to be declared when heat waves hit during Iraq's harsh summers.
The Iraqi Meteorological Department has said that this week's highs were well above average for this time of year. The heat is expected to decline nationwide, but a similarly unforgiving heat wave is expected next month.
High temperatures in summer are common in Iraq, and endemic electricity outages make life harder for Iraqis when temperatures soar. To cope with the heat, Iraqis either stay indoors or swim in rivers. In some public places, showers are set up for those who want to cool down.
The heat waves in recent years only added to the woes Iraqis have endured since the 2003 U.S.-led invasion, including daily violence, political wrangling, poor public services, a massive exodus abroad of professionals and high rates of serious crime like kidnappings for ransom, armed robberies and contract killings.