The Transport Management Centre is urging motorists to avoid all non-essential travel, with major routes closed across the region.
Spokesman, David Wright, says there is currently no access to Queensland from New South Wales via the coastal road or the main inland routes.
He says the Kamilaroi Highway is closed about 10-kilometres west of Breeza to light vehicles, the Newell is shut at Boggabilla and Moree, and landslips have closed the Gwydir Highway.
David Wright says if you can stay at home today, you should.
"Getting to Queensland is a real challenge because the Gwydir Highway is closed 70km west of Grafton at Jackadgery and Armidale Road is closed as well," he said.
"The Newell Highway is closed between Moree and Boggabilla, meaning there's no access to the Newell Highway from Queensland and the Kamilaroi Highway is closed around 10km west of Breeza to light vehicles."
The publican at the Royal Hotel in Gurley, Alan Young, says the heavy rain and road closures around Moree, Narrabri and Boggabilla have seen dozens of truckies pull into his hotel.
Gurley is located on the Newell Highway, between Moree and Narrabri.
Alan Young says there's been significant rain fall in the last two days and even the big vehicles are now stranded.
"There's water laying here three foot deep because there was an average of three inches an hour," he said.
"We've got four, eight, ten, twelve, fourteen, sixteen trucks so far and we've got another ten on their way from Narrabri, and here come some more."
Among the long-haul truckies who's unable to reach his destination because of the flooding is Billy.
He's travelling from Victoria to Brisbane.
Billy says he left Victoria on Wednesday and thought everything would be fine on the inland route.
He says that turned out not to be so, and says there's now at least two dozen trucks pulled up alongside him at the Gurley pub, where they expect to be stuck for the next day or so.
"Well, I've come from Shepparton and we're going to Brisbane, but things are not looking very good," he said.
"There's water everywhere and it looks like there's fog everywhere because you can only see only 100 yards over to where the big stockpiles of grain are, you can't see the mountains or anything."
The Minister for Western NSW, and member for Barwon, Kevin Humphries, drove to Moree from Coonabarabran on Wednesday along the Newell Highway.
He says there's been substantial rain in the area and travellers should just stay put for a while, until the water subsides and roads re-open.
"The amount of rain we've had up the Newell is coming in a big hurry and [RMS and council staff] are just having a bit of trouble getting the signs up, so there's quite a lot of roads closed," he said.
"People just need to be very careful and, as I say, if you don't need to be on the road just stay off the road, because you won't get too far."
© ABC 2013
00:33 EDT Severe thunderstorms and damaging winds caused chaos across Sydney on Sunday, with the SES responding to more than 550 jobs, mainly roof damage from heavy rain and strong winds.