The summer heat set a new all-time temperature record in Moscow on Thursday, a leading forecaster said, adding that the unprecedentedly long heat wave could be interrupted already on Friday.

Temperatures hit 37.7 degrees Celsius, beating the previous record set Monday, said the Fobos forecasting center, which provides weather data to the country's top media outlets.

At Domodedovo Airport outside Moscow, temperatures soared to 38.7 Celsius, Fobos said.

The adverse effects of the severe heat, which has been menacing Muscovites since late June, are aggravated by heavy smog that has blanketed the city and is caused mostly by burning peat in forests surrounding Moscow.

Russia's chief lung doctor, Alexander Chuchalin, warned on Wednesday that walking in the streets of Moscow is like smoking two packs of cigarettes every few hours because of the large concentration of toxins in the air.

Mineral water and soft drinks are selling like hot cakes in Moscow, while many pharmacies have run out of oxygen sprays.

Elsewhere in Russia, a drought unseen for all 130 years of weather observation has killed crops on an area the size of Hungary, leading the government to impose a state of emergency in 23 regions.

But after suffering from the suffocating heat for nearly six weeks, Muscovites may finally get a breather on Friday when a cold atmospheric front is expected to bring extreme temperatures down to about 30 degrees Celsius, Fobos said.

The fall in temperatures will be accompanied by heavy rainshowers and thunderstorms that are expected to reduce smog.

In Finland, a record temperature of 37 C was measured on Thursday, the Finnish Meteorological Institute said.

"According to preliminary observations, the highest-ever temperature record has been measured today, when the temperature at Joensuu Airport rose at 4 p.m. to 37 Celsius," the institute said on its web site.

Joensuu is located in eastern Finland, 437 kilometers northeast of Helsinki.

The previous temperature record was 35.9 C from July 1914, in the western coastal city of Turku.