The situation was particularly critical in the Lower Austrian district of Waidhofen an der Thaya, said Franz Schuster, who is helping to coordinate the local government's rescue effort.
Throughout the region, located close to the border with the Czech Republic, water has damaged homes and blocked streets, Austrian broadcaster ORF reported.
Images from the region showed rescue workers in rowboats and others wading through streets with water at thigh-high levels, the AP reports.
Poor weather conditions early Friday prevented the use of helicopters in the relief effort, Schuster said. The weather had improved somewhat by the late morning, Austrian radio reported.
Rescue workers evacuated some 100 people in the town Raabs, where the central square was under about a meter (40 inches) of water, ORF reported.
The level of the Thaya river rose by a meter (40 inches) in one hour early Friday, according to ORF. Schuster said it was impossible to gauge the river's current water level since it had overflowed but noted it had already surpassed the level reached during flooding in March.
In a weary world of endless US military interventions, sanctions, trade tariffs and chaos, let’s pause and take stock of the shining house on the hill