The mercury touched 37.8 degrees Celsius (100 Fahrenheit) in the western port city of Ventspils – the same location where the previous record was set a day earlier when temperatures reached 36.9 C – the state Environment, Geology and Meteorology Centre confirmed.
Prior to that the previous summer high was 36.4 C recorded in the country's south-eastern city of Daugavpils way back in 1943.
Though high temperatures were also recorded in neighbouring Estonia and Lithuania, Latvia was bearing the brunt of the heatwave, which has caused emergency services to urge the public to take extra care near water after a spate of drownings and in particular to keep an eye on children close tot he water's edge.
A warm July resulted in rescuers pulling 30 victims of drowning from lakes and rivers during the month, bringing the annual death toll to 94 with fears even higher temperatures could increase the trend.
However, forecasters predict temperatures are likely to slowly decline following Monday's peak.