The US is sending firefighting equipment to Russia to help officials battle 500 wildfires burning across the country.
President Barack Obama called Russian President Dmitry Medvedev on Thursday to express his condolences for the losses his country has suffered.
The wildfires have been sparked by the hottest summer ever recorded in Russia, with Moscow's death rate doubling to 700 people a day.
The White House said several US agencies, including the Defence Department, and the state of California are airlifing firefighting equipment to Russia to help combat the fires.
Heavy downpours on Friday cooled Moscow after weeks of no rain and unprecedented heat but did not quell the wildfires still raging around the Russian capital.
The city remains largely free of the clouds of suffocating smog that affected it earlier, but weather experts say smoke from burning forests and peat bogs may choke the city later if the wind direction changes.
Russia's Emergency Situations Ministry said its teams have managed to reduce the area covered by wildfires, but more than 500 are continuing to burn across the country, including 29 around Moscow. It said about 14,000 firefighters are battling blazes around the Russian capital.
A new wildfire also started east of the country's top nuclear research facility in Sarov, 300 miles east of Moscow. The blaze spread quickly, prompting firefighters in the region to call reinforcements from neighbouring areas, according to the region's emergency headquarters.
Earlier this month, massive wildfires around Sarov, the birthplace of Soviet nuclear weapons, prompted the nation's nuclear agency to move all explosive and radioactive material as a precaution. Reinforcements, including aircraft and robots, helped stem the blazes.
Another potential danger comes from wildfires in areas contaminated by the 1986 Chernobyl nuclear disaster that may raise radioactive particles into the air and spread them over a broader territory. The authorities insisted all wildfires in the Chernobyl-affected regions have been quickly dealt with and radiation levels have remained normal.