With Japan suffering its worst heatwave since records began in 1898, haunted houses or "obake yashiki" are doing a roaring trade as the traditional summertime venues to cool off.

Ghost houses are set up especially for the summer in amusements parks in Japan with the tradition linked to Japanese Buddhism which views August as the time when ancestral spirits may return for a visit and Japanese visit their elders' graves.

This year ghost houses have reported dramatic increases in visitor numbers as they tap into the Japanese tradition of also telling scary stories to send shivers down people's spines and cool them down.

With temperatures still running high, Tokyo Dome City Attractions has extended its ghost house opening by a month.

Japanese naturally connect summer with being scared and feeling cool thanks to that," said the Dome's spokesman Yoshinosuke Goto.

"We have run the summer ghost house here for last 19 years straight, but this year has been special and we have had many more customers thanks to the hot weather."

In the past six weeks over 40,000 students, couples and company workers have flocked to the ghost house.

"It was frightening! We were so tense we broke out in a cold sweat," said Takuya Fujita and Mai Uchino, service company workers, clinging to each other after leaving the haunted house.

"We came here because it's very hot and we wanted feel a chill!"

Other amusement parks have also reported higher customer numbers. The "obake yashiki" in Yomiuri Land amusement park in Tokyo said numbers were up 15 percent from last year with 37,000 visitors.

Japan is facing its hottest summer since the records began, with temperatures reaching 38.3 Celsius (100.9 Fahrenheit), leading to a reported 132 deaths and more than 30,000 people taken to hospital with heatstroke.

The Japanese Meteorological Agency said on Wednesday the average temperature between June and August was 1.64 degrees Celsius above average for the period. The office did not give the actual average temperature.