The interior ministry was forced to issue public appeals for Nairobi’s notoriously congested traffic to give way to trucks ferrying water to the airport after firefighters tackling the blaze ran “dangerously low on water”.
Some 16,000 passengers usually transit through JKIA every day, according to official figures.
The airport is a regional hub for east Africa, with many long-distance international flights landing there to connect to countries across the region.
There were no casualties in the fire but two people – an airport worker and a passenger – were taken to hospital due to smoke inhalation.
August is one of Kenya’s busiest months for tourism, a key industry for the country, as foreign travellers fly in to see its wildlife and enjoy the white sand beaches on its Indian Ocean coast.
The airport offers direct connections to Europe, the Middle East, the Far East and other African cities.