Moult has netted twice this season and will return to Northampton on March 7 after helping with Nuneaton's battle against relegation.
"This move will do Louis good," Northampton manager Aidy Boothroyd said.
"He has been a little unfortunate not to play more than he has, but competition for places is tough up front at the moment and he needs regular football.
"I am sure he will do well for Nuneaton and we will monitor his progress."
Northampton are currently eighth in League Two.