The impressive Toby Flood and Jamie Noon midfield partnership stole the headlines, Noon scoring a try in each half and Flood kicking seven points.
But it was the dominance of the Falcons’ forwards that thwarted the Scarlets, controlling possession in poor weather.
The visitors managed penalties from Ceiron Thomas (2) and Barry Davies, but a late John Rudd try crowned the win.
Scarlets Director of Rugby Phil Davies was not happy with the performance.
“That was the poorest we’ve played all season. We’ve been playing in sunshine so far, but in the wind and rain we got stuffed.
“Newcastle were terrific, but we do have a power game and a kicking game – we just didn’t show it.
“It’s all about learning, we’ll pick ourselves off the floor and go again. We can win at Sale, but we have the Heineken Cup to concentrate on first.”