Heavy rain has caused problems on roads and in town centres across the county.
Northamptonshire Fire and Rescue Service have described Sunday as a very busy day, saying officers had been out inspecting and offering advice to residents caught out by the downpours.
In Wellingborough, firefighters were called to a pump out a flooded subway linking Shelley Road with the Park Farm industrial estate.
Niort Way, the A509 to the north-west of Wellingborough town centre, was also shut off to traffic by police.
In a statement, the fire service said flooding was “threatening to affect many properties in the county”. Weather forecasters have suggested the worst of the wet weather has passed for the time being.