 Budapest is having a hotter summer than last year |
Anna Paldy, deputy director of the National Institute of Environmental Health, told the BBC that the figure included 230 deaths in central Hungary.
The deaths - from 15 to 22 July - were caused by heatstroke, cardiovascular problems and other illnesses aggravated by the heat, she said.
Some 30 people have also died in the heatwave in neighbouring Romania.
Ms Paldy told the BBC News website that the death rate from heat in Hungary was the highest in recent years.
The daily mean temperature in the past week had reached 30C, she said.
In the southern city of Kiskunhalas, the temperature reached a record high of 41.9C.
The data came from hospitals and doctors in Budapest and the county of Pest, which the researchers then extrapolated for the whole country. Most of the deaths were among elderly people.
Regional woes
South-Eastern Europe is reeling from the hot weather, which has been blamed for widespread forest fires and has also caused economic hardship.
 Forest fires have raged across Greece amid soaring temperatures |
Parts of northern Europe have meanwhile seen vast floods and heavy rainfall - sparking fears that climate change may be to blame for the extreme weather.
Unusually high temperatures of more than 40C (104F) have been recorded in several parts of southern and eastern Europe.
On Monday, temperatures of 45C (113F) were recorded in Bulgaria - the hottest since records began, officials said.
Hundreds of forest fires have been reported in Greece, where two pilots died on Monday after a water-bombing aircraft they were flying over a forest fire crashed.
Another such aircraft flying over a forest fire in Italy crashed on Monday, killing three people.
In the Former Yugoslav Republic of Macedonia, thousands of firefighters, soldiers and local people battled throughout Monday night to stop a forest fire from reaching the country's second-largest city, Bitola.
SUMMER 2006  In a 'normal' summer, the Atlantic jetstream directs areas of low pressure, which bring cloud and rain, to the north of the UK. High pressure systems over Europe and the Atlantic bring warm, settled conditions. Pressure chart: 29/6/06. Source: Met Office |
SUMMER 2007  This summer, the jetstream is flowing further south allowing low pressure systems to sweep straight over the centre of Britain. It is also pulling in warmer air from the sub-tropics and Africa which is sweeping over south-eastern Europe. Pressure chart: 24/07/07. Source: Met Office |
