Work to raise Drayton Road, the main road into Muchelney, was due to have been finished at the end of last month.
Bad weather now means it will not be completed until mid February, a Somerset County Council spokesman said.
Last winter large parts of the Levels were deluged with flooding, leaving villagers cut off for two months and a trunk road closed for several weeks.
A 547 yard-stretch (500m) of Drayton Road is being raised by more than 3.9 ft (120 cm) at its lowest point.
A council spokesman said: "We have been saying since the beginning of November that the Muchelney road raising was likely to run into the New Year.
"As things stand, we are hoping to be able to complete the works in February. However, as they have been from the beginning, all scheduled completion times will be subject to factors such as the weather."
A scheme to prevent a community on the Somerset Levels from being cut off by flooding has been delayed.