The test is taking place due to the replacement of the siren at the Vale Centre site on Stubbing Holme Road. The siren test will last for two minutes.
Christian Merriman, Environment Agency flood risk advisor for Calderdale said:
The new siren is being moved approximately 10 metres from its existing location because of work on a wall as part of the Hebden Bridge Flood Alleviation Scheme. The siren is being tested to ensure it is working effectively in its new position.
Residents and businesses do not need to take any action when the sirens sound during the testing but the siren should be treated seriously if sounded at any other time.
With an audibility level similar to that used by emergency vehicles, the Environment Agency uses the sirens to warn people of possible imminent flooding from the River Calder that runs through the town.
The sirens help the community be as prepared as possible for any risk of flooding.