According to AccuWeather, the temperature in the Hungarian capital is expected to reach a high of 32 degrees Celsius on Wednesday.
"... so we will be moving the (5,000m) heats to 7pm on Wednesday evening," the governing body said, adding that the heats for the men's and women's 200m races would begin earlier on Wednesday.
Gudaf Tsegay of Ethiopia is the reigning world 5,000m champion.
Her bid to retain the title will see her come up against Kenya's Faith Kipyegon - the world record holder in the distance.
Reporting by Lori Ewing, writing by Aadi Nair, editing by Pritha SarkarOur Standards: The Thomson Reuters Trust Principles.
Persons:
Sifan Hassan, Aleksandra Szmigiel, AccuWeather, Gudaf, Kenya's Faith Kipyegon, Lori Ewing, Aadi Nair, Pritha Sarkar
Organizations:
National Athletics Centre, Athletics, Kenya's, Thomson
Locations:
Budapest, Hungary, Netherlands, Ethiopia