TMZ Sports has learned ... a temporary OurCalling homeless shelter in Dallas was overwhelmed this week as hundreds of people in need tried to escape the crippling effects of the nasty weather that's hit the region.

And, when Dak found out, we're told he reached out with a huge helping hand.

Neither the org. nor Dak's camp would reveal the donation amount -- but it's fair to say everyone is more than happy with the quarterback's gesture.

A spokesperson for OurCalling says Dak's donation was able to help around 1,000 people Thursday ... and those who got the aid were thrilled.

The spokesperson says many of them were in Dallas Cowboys jackets and sweatshirts ... and were so pumped to hear Dak helped, they were high-fiving at the shelter.

"It means the world to the homeless community," the spokesperson said.

Of course, Dak's charitable move means so much more when you consider he might not even be playing in Dallas in a few months.

Prescott is currently in a contract dispute with the Cowboys ... and there's speculation it could lead to a divorce.

So, big ups to the QB for setting that all aside and helping those in need regardless.