Flames shot up from a manhole cover after a short circuit. The fire, believed to be electrical, happened in Station Road, Portslade.
A fire crew from Newhaven, covering at Roedean because of the day’s extreme weather, put the fire out using a dry extinguisher at 7.30am on Monday.
The fire is believed to have been caused by flood water entering electrics under the pavement.
Richard Fowler, of East Sussex Fire and Rescue Service, said: “Such fires are normally caused by excess water entering underground electrical boxes, which causes a short circuit and a fire.”