Bruno Guimaraes' 90th-minute strike rescued the Magpies from what looked like a damaging draw, and Howe believes the timing of the goal could have a ripple effect.
"Late goals don't just affect the game you've won, they affect mood and belief going forward," Howe said.
"It can have a big knock-on effect. We've had heartbreak the other way. This felt like a massive moment for us. We found a way to win."
Newcastle's win was just their third of the season and saw them climb provisionally to 10th in the table.
Howe wants more though, after last season's fifth-place finish and a League Cup victory.
The Magpies were looking to get their league campaign back on track after last weekend's disappointing 2-1 loss at Brighton, but were buoyed by their emphatic 3-0 Champions League victory over Benfica midweek.
Howe had talked of reigniting Newcastle's Premier League push — and his side backed up that ambition with a purposeful start, with Jacob Murphy scoring in the 18th minute.
Sasa Lukic drew the visitors level in the 56th minute and the game looked to be heading towards a draw before Guimaraes' late-game heroics.
Substitute William Osula drove to the edge of the box, but his shot was parried into the path of Guimaraes by goalkeeper Bernd Leno, and the Brazilian poked it in from close range.
"It's one I'll remember, that's for sure," Howe said. "You always remember when you win late, and it was a priceless win for us... a big three points."
Howe had praised Guimaraes' durability in logging thousands of miles to play for club and country in his pre-game press conference on Friday, pointing out that his captain "very rarely lets you down."
The midfielder proved his point at St James' Park.
"I feel unbelievable. We were very tired from Wednesday's game and I think we had to learn how to finish the game," Guimaraes said.
"I'm happy in the end we scored a goal. The last few games we have been punished at the end - by Arsenal, Liverpool.
"Will Osula, he came, he shot and I was ready for the rebound in my 150th start for this club. Now I just want to rest for a bit because I am very tired.
"We cannot play the perfect game every time but we need to find the three points and we did this today. Very pleased for everyone. This is the Newcastle I know, we fight until the end."