Forest are likely to have to pay around £750,00 when the deal is made permanent once the transfer window opens.
Wycombe boss John Gorman told the club's official website, wycombewanderers.co.uk: "Although we didn't want to lose him, this is a financial move that everyone has to understand. Nathan has kept going all the way through the speculation and he's been a pleasure to work with.
"We wish him all the best."