Weale let Paul McKenna's weak shot squirm through his hands six minutes from time to gift Forest the victory
Billy Davies' side were second best for large periods in a scruffy game.
After a high-octane start which saw two goals in the space of five first-half minutes from Marcus Tudgay and Matt Oakley, the match appeared to be petering out as players wilted in the spring sunshine.
Robert Earnshaw then pounced to put the hosts back in front with less than 20 minutes left, only for substitute Darius Vassell to level 60 seconds later for Sven-Goran Eriksson's men.
Both sides were guilty of surrendering possession cheaply and a draw looked likely until skipper McKenna was handed the winner to give Forest just a second win in 12 games.
Source: PA
Source: PA